/*!
  * https://github.com/paulmillr/es6-shim
  * @license es6-shim Copyright 2013-2015 by Paul Miller (http://paulmillr.com)
  *   and contributors,  MIT License
  * es6-shim: v0.27.1
  * see https://github.com/paulmillr/es6-shim/blob/0.27.1/LICENSE
  * Details and documentation:
  * https://github.com/paulmillr/es6-shim/
  */

// UMD (Universal Module Definition)
// see https://github.com/umdjs/umd/blob/master/returnExports.js
(function (root, factory) {
  /*global define, module, exports */
  if (typeof define === 'function' && define.amd) {
    // AMD. Register as an anonymous module.
    define(factory);
  } else if (typeof exports === 'object') {
    // Node. Does not work with strict CommonJS, but
    // only CommonJS-like enviroments that support module.exports,
    // like Node.
    module.exports = factory();
  } else {
    // Browser globals (root is window)
    root.returnExports = factory();
  }
}(this, function () {
  'use strict';

  var not = function notThunker(func) {
    return function notThunk() { return !func.apply(this, arguments); };
  };
  var throwsError = function (func) {
    try {
      func();
      return false;
    } catch (e) {
      return true;
    }
  };
  var valueOrFalseIfThrows = function valueOrFalseIfThrows(func) {
    try {
      return func();
    } catch (e) {
      return false;
    }
  };

  var isCallableWithoutNew = not(throwsError);
  var arePropertyDescriptorsSupported = function () {
    // if Object.defineProperty exists but throws, it's IE 8
    return !throwsError(function () { Object.defineProperty({}, 'x', {}); });
  };
  var supportsDescriptors = !!Object.defineProperty && arePropertyDescriptorsSupported();

  var defineProperty = function (object, name, value, force) {
    if (!force && name in object) { return; }
    if (supportsDescriptors) {
      Object.defineProperty(object, name, {
        configurable: true,
        enumerable: false,
        writable: true,
        value: value
      });
    } else {
      object[name] = value;
    }
  };

  // Define configurable, writable and non-enumerable props
  // if they don’t exist.
  var defineProperties = function (object, map) {
    Object.keys(map).forEach(function (name) {
      var method = map[name];
      defineProperty(object, name, method, false);
    });
  };

  // Simple shim for Object.create on ES3 browsers
  // (unlike real shim, no attempt to support `prototype === null`)
  var create = Object.create || function (prototype, properties) {
    function Prototype() {}
    Prototype.prototype = prototype;
    var object = new Prototype();
    if (typeof properties !== 'undefined') {
      defineProperties(object, properties);
    }
    return object;
  };

  var supportsSubclassing = function (C, f) {
    if (!Object.setPrototypeOf) { return false; /* skip test on IE < 11 */ }
    return valueOrFalseIfThrows(function () {
      var Sub = function Subclass(arg) {
        var o = new C(arg);
        Object.setPrototypeOf(o, Subclass.prototype);
        return o;
      };
      Sub.prototype = create(C.prototype, {
        constructor: { value: C }
      });
      return f(Sub);
    });
  };

  var startsWithRejectsRegex = function () {
    return String.prototype.startsWith && throwsError(function () {
      /* throws if spec-compliant */
      '/a/'.startsWith(/a/);
    });
  };
  var startsWithHandlesInfinity = (function () {
    return String.prototype.startsWith && 'abc'.startsWith('a', Infinity) === false;
  }());

  /*jshint evil: true */
  var getGlobal = new Function('return this;');
  /*jshint evil: false */

  var globals = getGlobal();
  var globalIsFinite = globals.isFinite;
  var hasStrictMode = (function () { return this === null; }.call(null));
  var startsWithIsCompliant = startsWithRejectsRegex() && startsWithHandlesInfinity;
  var _indexOf = Function.call.bind(String.prototype.indexOf);
  var _toString = Function.call.bind(Object.prototype.toString);
  var _hasOwnProperty = Function.call.bind(Object.prototype.hasOwnProperty);
  var ArrayIterator; // make our implementation private
  var noop = function () {};

  var Symbol = globals.Symbol || {};
  var symbolSpecies = Symbol.species || '@@species';
  var Type = {
    object: function (x) { return x !== null && typeof x === 'object'; },
    string: function (x) { return _toString(x) === '[object String]'; },
    regex: function (x) { return _toString(x) === '[object RegExp]'; },
    symbol: function (x) {
      return typeof globals.Symbol === 'function' && typeof x === 'symbol';
    }
  };

  var numberIsNaN = Number.isNaN || function isNaN(value) {
    // NaN !== NaN, but they are identical.
    // NaNs are the only non-reflexive value, i.e., if x !== x,
    // then x is NaN.
    // isNaN is broken: it converts its argument to number, so
    // isNaN('foo') => true
    return value !== value;
  };
  var numberIsFinite = Number.isFinite || function isFinite(value) {
    return typeof value === 'number' && globalIsFinite(value);
  };

  var Value = {
    getter: function (object, name, getter) {
      if (!supportsDescriptors) {
        throw new TypeError('getters require true ES5 support');
      }
      Object.defineProperty(object, name, {
        configurable: true,
        enumerable: false,
        get: getter
      });
    },
    proxy: function (originalObject, key, targetObject) {
      if (!supportsDescriptors) {
        throw new TypeError('getters require true ES5 support');
      }
      var originalDescriptor = Object.getOwnPropertyDescriptor(originalObject, key);
      Object.defineProperty(targetObject, key, {
        configurable: originalDescriptor.configurable,
        enumerable: originalDescriptor.enumerable,
        get: function getKey() { return originalObject[key]; },
        set: function setKey(value) { originalObject[key] = value; }
      });
    },
    redefine: function (object, property, newValue) {
      if (supportsDescriptors) {
        var descriptor = Object.getOwnPropertyDescriptor(object, property);
        descriptor.value = newValue;
        Object.defineProperty(object, property, descriptor);
      } else {
        object[property] = newValue;
      }
    },
    preserveToString: function (target, source) {
      defineProperty(target, 'toString', source.toString.bind(source), true);
    }
  };

  var overrideNative = function overrideNative(object, property, replacement) {
    var original = object[property];
    defineProperty(object, property, replacement, true);
    Value.preserveToString(object[property], original);
  };

  // This is a private name in the es6 spec, equal to '[Symbol.iterator]'
  // we're going to use an arbitrary _-prefixed name to make our shims
  // work properly with each other, even though we don't have full Iterator
  // support.  That is, `Array.from(map.keys())` will work, but we don't
  // pretend to export a "real" Iterator interface.
  var $iterator$ = Type.symbol(Symbol.iterator) ? Symbol.iterator : '_es6-shim iterator_';
  // Firefox ships a partial implementation using the name @@iterator.
  // https://bugzilla.mozilla.org/show_bug.cgi?id=907077#c14
  // So use that name if we detect it.
  if (globals.Set && typeof new globals.Set()['@@iterator'] === 'function') {
    $iterator$ = '@@iterator';
  }
  var addIterator = function (prototype, impl) {
    var implementation = impl || function iterator() { return this; };
    var o = {};
    o[$iterator$] = implementation;
    defineProperties(prototype, o);
    if (!prototype[$iterator$] && Type.symbol($iterator$)) {
      // implementations are buggy when $iterator$ is a Symbol
      prototype[$iterator$] = implementation;
    }
  };

  // taken directly from https://github.com/ljharb/is-arguments/blob/master/index.js
  // can be replaced with require('is-arguments') if we ever use a build process instead
  var isArguments = function isArguments(value) {
    var str = _toString(value);
    var result = str === '[object Arguments]';
    if (!result) {
      result = str !== '[object Array]' &&
        value !== null &&
        typeof value === 'object' &&
        typeof value.length === 'number' &&
        value.length >= 0 &&
        _toString(value.callee) === '[object Function]';
    }
    return result;
  };

  var safeApply = Function.call.bind(Function.apply);

  var ES = {
    // https://people.mozilla.org/~jorendorff/es6-draft.html#sec-call-f-v-args
    Call: function Call(F, V) {
      var args = arguments.length > 2 ? arguments[2] : [];
      if (!ES.IsCallable(F)) {
        throw new TypeError(F + ' is not a function');
      }
      return safeApply(F, V, args);
    },

    RequireObjectCoercible: function (x, optMessage) {
      /* jshint eqnull:true */
      if (x == null) {
        throw new TypeError(optMessage || 'Cannot call method on ' + x);
      }
    },

    TypeIsObject: function (x) {
      /* jshint eqnull:true */
      // this is expensive when it returns false; use this function
      // when you expect it to return true in the common case.
      return x != null && Object(x) === x;
    },

    ToObject: function (o, optMessage) {
      ES.RequireObjectCoercible(o, optMessage);
      return Object(o);
    },

    IsCallable: function (x) {
      // some versions of IE say that typeof /abc/ === 'function'
      return typeof x === 'function' && _toString(x) === '[object Function]';
    },

    ToInt32: function (x) {
      return ES.ToNumber(x) >> 0;
    },

    ToUint32: function (x) {
      return ES.ToNumber(x) >>> 0;
    },

    ToNumber: function (value) {
      if (_toString(value) === '[object Symbol]') {
        throw new TypeError('Cannot convert a Symbol value to a number');
      }
      return +value;
    },

    ToInteger: function (value) {
      var number = ES.ToNumber(value);
      if (numberIsNaN(number)) { return 0; }
      if (number === 0 || !numberIsFinite(number)) { return number; }
      return (number > 0 ? 1 : -1) * Math.floor(Math.abs(number));
    },

    ToLength: function (value) {
      var len = ES.ToInteger(value);
      if (len <= 0) { return 0; } // includes converting -0 to +0
      if (len > Number.MAX_SAFE_INTEGER) { return Number.MAX_SAFE_INTEGER; }
      return len;
    },

    SameValue: function (a, b) {
      if (a === b) {
        // 0 === -0, but they are not identical.
        if (a === 0) { return 1 / a === 1 / b; }
        return true;
      }
      return numberIsNaN(a) && numberIsNaN(b);
    },

    SameValueZero: function (a, b) {
      // same as SameValue except for SameValueZero(+0, -0) == true
      return (a === b) || (numberIsNaN(a) && numberIsNaN(b));
    },

    IsIterable: function (o) {
      return ES.TypeIsObject(o) && (typeof o[$iterator$] !== 'undefined' || isArguments(o));
    },

    GetIterator: function (o) {
      if (isArguments(o)) {
        // special case support for `arguments`
        return new ArrayIterator(o, 'value');
      }
      var itFn = o[$iterator$];
      if (!ES.IsCallable(itFn)) {
        throw new TypeError('value is not an iterable');
      }
      var it = itFn.call(o);
      if (!ES.TypeIsObject(it)) {
        throw new TypeError('bad iterator');
      }
      return it;
    },

    IteratorNext: function (it) {
      var result = arguments.length > 1 ? it.next(arguments[1]) : it.next();
      if (!ES.TypeIsObject(result)) {
        throw new TypeError('bad iterator');
      }
      return result;
    },

    Construct: function (C, args) {
      // CreateFromConstructor
      var obj;
      if (ES.IsCallable(C[symbolSpecies])) {
        obj = C[symbolSpecies]();
      } else {
        // OrdinaryCreateFromConstructor
        obj = create(C.prototype || null);
      }
      // Mark that we've used the es6 construct path
      // (see emulateES6construct)
      defineProperties(obj, { _es6construct: true });
      // Call the constructor.
      var result = ES.Call(C, obj, args);
      return ES.TypeIsObject(result) ? result : obj;
    },

    CreateHTML: function (string, tag, attribute, value) {
      var S = String(string);
      var p1 = '<' + tag;
      if (attribute !== '') {
        var V = String(value);
        var escapedV = V.replace(/"/g, '&quot;');
        p1 += ' ' + attribute + '="' + escapedV + '"';
      }
      var p2 = p1 + '>';
      var p3 = p2 + S;
      return p3 + '</' + tag + '>';
    }
  };

  var emulateES6construct = function (o) {
    if (!ES.TypeIsObject(o)) { throw new TypeError('bad object'); }
    var object = o;
    // es5 approximation to es6 subclass semantics: in es6, 'new Foo'
    // would invoke Foo.@@species to allocation/initialize the new object.
    // In es5 we just get the plain object.  So if we detect an
    // uninitialized object, invoke o.constructor.@@species
    if (!object._es6construct) {
      if (object.constructor && ES.IsCallable(object.constructor[symbolSpecies])) {
        object = object.constructor[symbolSpecies](object);
      }
      defineProperties(object, { _es6construct: true });
    }
    return object;
  };

  // Firefox 31 reports this function's length as 0
  // https://bugzilla.mozilla.org/show_bug.cgi?id=1062484
  if (String.fromCodePoint && String.fromCodePoint.length !== 1) {
    var originalFromCodePoint = Function.apply.bind(String.fromCodePoint);
    overrideNative(String, 'fromCodePoint', function fromCodePoint(codePoints) { return originalFromCodePoint(this, arguments); });
  }

  var StringShims = {
    fromCodePoint: function fromCodePoint(codePoints) {
      var result = [];
      var next;
      for (var i = 0, length = arguments.length; i < length; i++) {
        next = Number(arguments[i]);
        if (!ES.SameValue(next, ES.ToInteger(next)) || next < 0 || next > 0x10FFFF) {
          throw new RangeError('Invalid code point ' + next);
        }

        if (next < 0x10000) {
          result.push(String.fromCharCode(next));
        } else {
          next -= 0x10000;
          result.push(String.fromCharCode((next >> 10) + 0xD800));
          result.push(String.fromCharCode((next % 0x400) + 0xDC00));
        }
      }
      return result.join('');
    },

    raw: function raw(callSite) {
      var cooked = ES.ToObject(callSite, 'bad callSite');
      var rawString = ES.ToObject(cooked.raw, 'bad raw value');
      var len = rawString.length;
      var literalsegments = ES.ToLength(len);
      if (literalsegments <= 0) {
        return '';
      }

      var stringElements = [];
      var nextIndex = 0;
      var nextKey, next, nextSeg, nextSub;
      while (nextIndex < literalsegments) {
        nextKey = String(nextIndex);
        nextSeg = String(rawString[nextKey]);
        stringElements.push(nextSeg);
        if (nextIndex + 1 >= literalsegments) {
          break;
        }
        next = nextIndex + 1 < arguments.length ? arguments[nextIndex + 1] : '';
        nextSub = String(next);
        stringElements.push(nextSub);
        nextIndex++;
      }
      return stringElements.join('');
    }
  };
  defineProperties(String, StringShims);
  if (String.raw({ raw: { 0: 'x', 1: 'y', length: 2 } }) !== 'xy') {
    // IE 11 TP has a broken String.raw implementation
    overrideNative(String, 'raw', StringShims.raw);
  }

  // Fast repeat, uses the `Exponentiation by squaring` algorithm.
  // Perf: http://jsperf.com/string-repeat2/2
  var stringRepeat = function repeat(s, times) {
    if (times < 1) { return ''; }
    if (times % 2) { return repeat(s, times - 1) + s; }
    var half = repeat(s, times / 2);
    return half + half;
  };
  var stringMaxLength = Infinity;

  var StringPrototypeShims = {
    repeat: function repeat(times) {
      ES.RequireObjectCoercible(this);
      var thisStr = String(this);
      var numTimes = ES.ToInteger(times);
      if (numTimes < 0 || numTimes >= stringMaxLength) {
        throw new RangeError('repeat count must be less than infinity and not overflow maximum string size');
      }
      return stringRepeat(thisStr, numTimes);
    },

    startsWith: function startsWith(searchString) {
      ES.RequireObjectCoercible(this);
      var thisStr = String(this);
      if (Type.regex(searchString)) {
        throw new TypeError('Cannot call method "startsWith" with a regex');
      }
      var searchStr = String(searchString);
      var startArg = arguments.length > 1 ? arguments[1] : void 0;
      var start = Math.max(ES.ToInteger(startArg), 0);
      return thisStr.slice(start, start + searchStr.length) === searchStr;
    },

    endsWith: function endsWith(searchString) {
      ES.RequireObjectCoercible(this);
      var thisStr = String(this);
      if (Type.regex(searchString)) {
        throw new TypeError('Cannot call method "endsWith" with a regex');
      }
      var searchStr = String(searchString);
      var thisLen = thisStr.length;
      var posArg = arguments.length > 1 ? arguments[1] : void 0;
      var pos = typeof posArg === 'undefined' ? thisLen : ES.ToInteger(posArg);
      var end = Math.min(Math.max(pos, 0), thisLen);
      return thisStr.slice(end - searchStr.length, end) === searchStr;
    },

    includes: function includes(searchString) {
      var position = arguments.length > 1 ? arguments[1] : void 0;
      // Somehow this trick makes method 100% compat with the spec.
      return _indexOf(this, searchString, position) !== -1;
    },

    codePointAt: function codePointAt(pos) {
      ES.RequireObjectCoercible(this);
      var thisStr = String(this);
      var position = ES.ToInteger(pos);
      var length = thisStr.length;
      if (position >= 0 && position < length) {
        var first = thisStr.charCodeAt(position);
        var isEnd = (position + 1 === length);
        if (first < 0xD800 || first > 0xDBFF || isEnd) { return first; }
        var second = thisStr.charCodeAt(position + 1);
        if (second < 0xDC00 || second > 0xDFFF) { return first; }
        return ((first - 0xD800) * 1024) + (second - 0xDC00) + 0x10000;
      }
    }
  };
  defineProperties(String.prototype, StringPrototypeShims);

  if ('a'.includes('a', Infinity) !== false) {
    overrideNative(String.prototype, 'includes', StringPrototypeShims.includes);
  }

  var hasStringTrimBug = '\u0085'.trim().length !== 1;
  if (hasStringTrimBug) {
    delete String.prototype.trim;
    // whitespace from: http://es5.github.io/#x15.5.4.20
    // implementation from https://github.com/es-shims/es5-shim/blob/v3.4.0/es5-shim.js#L1304-L1324
    var ws = [
      '\x09\x0A\x0B\x0C\x0D\x20\xA0\u1680\u180E\u2000\u2001\u2002\u2003',
      '\u2004\u2005\u2006\u2007\u2008\u2009\u200A\u202F\u205F\u3000\u2028',
      '\u2029\uFEFF'
    ].join('');
    var trimRegexp = new RegExp('(^[' + ws + ']+)|([' + ws + ']+$)', 'g');
    defineProperties(String.prototype, {
      trim: function trim() {
        if (typeof this === 'undefined' || this === null) {
          throw new TypeError("can't convert " + this + ' to object');
        }
        return String(this).replace(trimRegexp, '');
      }
    });
  }

  // see https://people.mozilla.org/~jorendorff/es6-draft.html#sec-string.prototype-@@iterator
  var StringIterator = function (s) {
    ES.RequireObjectCoercible(s);
    this._s = String(s);
    this._i = 0;
  };
  StringIterator.prototype.next = function () {
    var s = this._s, i = this._i;
    if (typeof s === 'undefined' || i >= s.length) {
      this._s = void 0;
      return { value: void 0, done: true };
    }
    var first = s.charCodeAt(i), second, len;
    if (first < 0xD800 || first > 0xDBFF || (i + 1) === s.length) {
      len = 1;
    } else {
      second = s.charCodeAt(i + 1);
      len = (second < 0xDC00 || second > 0xDFFF) ? 1 : 2;
    }
    this._i = i + len;
    return { value: s.substr(i, len), done: false };
  };
  addIterator(StringIterator.prototype);
  addIterator(String.prototype, function () {
    return new StringIterator(this);
  });

  if (!startsWithIsCompliant) {
    // Firefox (< 37?) and IE 11 TP have a noncompliant startsWith implementation
    overrideNative(String.prototype, 'startsWith', StringPrototypeShims.startsWith);
    overrideNative(String.prototype, 'endsWith', StringPrototypeShims.endsWith);
  }

  var ArrayShims = {
    from: function from(iterable) {
      var mapFn = arguments.length > 1 ? arguments[1] : void 0;

      var list = ES.ToObject(iterable, 'bad iterable');
      if (typeof mapFn !== 'undefined' && !ES.IsCallable(mapFn)) {
        throw new TypeError('Array.from: when provided, the second argument must be a function');
      }

      var hasThisArg = arguments.length > 2;
      var thisArg = hasThisArg ? arguments[2] : void 0;

      var usingIterator = ES.IsIterable(list);
      // does the spec really mean that Arrays should use ArrayIterator?
      // https://bugs.ecmascript.org/show_bug.cgi?id=2416
      //if (Array.isArray(list)) { usingIterator=false; }

      var length;
      var result, i, value;
      if (usingIterator) {
        i = 0;
        result = ES.IsCallable(this) ? Object(new this()) : [];
        var it = usingIterator ? ES.GetIterator(list) : null;
        var iterationValue;

        do {
          iterationValue = ES.IteratorNext(it);
          if (!iterationValue.done) {
            value = iterationValue.value;
            if (mapFn) {
              result[i] = hasThisArg ? mapFn.call(thisArg, value, i) : mapFn(value, i);
            } else {
              result[i] = value;
            }
            i += 1;
          }
        } while (!iterationValue.done);
        length = i;
      } else {
        length = ES.ToLength(list.length);
        result = ES.IsCallable(this) ? Object(new this(length)) : new Array(length);
        for (i = 0; i < length; ++i) {
          value = list[i];
          if (mapFn) {
            result[i] = hasThisArg ? mapFn.call(thisArg, value, i) : mapFn(value, i);
          } else {
            result[i] = value;
          }
        }
      }

      result.length = length;
      return result;
    },

    of: function of() {
      return Array.from.call(this, arguments);
    }
  };
  defineProperties(Array, ArrayShims);

  // Given an argument x, it will return an IteratorResult object,
  // with value set to x and done to false.
  // Given no arguments, it will return an iterator completion object.
  var iteratorResult = function (x) {
    return { value: x, done: arguments.length === 0 };
  };

  // Our ArrayIterator is private; see
  // https://github.com/paulmillr/es6-shim/issues/252
  ArrayIterator = function (array, kind) {
      this.i = 0;
      this.array = array;
      this.kind = kind;
  };

  defineProperties(ArrayIterator.prototype, {
    next: function () {
      var i = this.i, array = this.array;
      if (!(this instanceof ArrayIterator)) {
        throw new TypeError('Not an ArrayIterator');
      }
      if (typeof array !== 'undefined') {
        var len = ES.ToLength(array.length);
        for (; i < len; i++) {
          var kind = this.kind;
          var retval;
          if (kind === 'key') {
            retval = i;
          } else if (kind === 'value') {
            retval = array[i];
          } else if (kind === 'entry') {
            retval = [i, array[i]];
          }
          this.i = i + 1;
          return { value: retval, done: false };
        }
      }
      this.array = void 0;
      return { value: void 0, done: true };
    }
  });
  addIterator(ArrayIterator.prototype);

  var ObjectIterator = function (object, kind) {
    this.object = object;
    // Don't generate keys yet.
    this.array = null;
    this.kind = kind;
  };

  function getAllKeys(object) {
    var keys = [];

    for (var key in object) {
      keys.push(key);
    }

    return keys;
  }

  defineProperties(ObjectIterator.prototype, {
    next: function () {
      var key, array = this.array;

      if (!(this instanceof ObjectIterator)) {
        throw new TypeError('Not an ObjectIterator');
      }

      // Keys not generated
      if (array === null) {
        array = this.array = getAllKeys(this.object);
      }

      // Find next key in the object
      while (ES.ToLength(array.length) > 0) {
        key = array.shift();

        // The candidate key isn't defined on object.
        // Must have been deleted, or object[[Prototype]]
        // has been modified.
        if (!(key in this.object)) {
          continue;
        }

        if (this.kind === 'key') {
          return iteratorResult(key);
        } else if (this.kind === 'value') {
          return iteratorResult(this.object[key]);
        } else {
          return iteratorResult([key, this.object[key]]);
        }
      }

      return iteratorResult();
    }
  });
  addIterator(ObjectIterator.prototype);

  // note: this is positioned here because it depends on ArrayIterator
  var arrayOfSupportsSubclassing = (function () {
    // Detects a bug in Webkit nightly r181886
    var Foo = function Foo(len) { this.length = len; };
    Foo.prototype = [];
    var fooArr = Array.of.apply(Foo, [1, 2]);
    return fooArr instanceof Foo && fooArr.length === 2;
  }());
  if (!arrayOfSupportsSubclassing) {
    overrideNative(Array, 'of', ArrayShims.of);
  }

  var ArrayPrototypeShims = {
    copyWithin: function copyWithin(target, start) {
      var end = arguments[2]; // copyWithin.length must be 2
      var o = ES.ToObject(this);
      var len = ES.ToLength(o.length);
      var relativeTarget = ES.ToInteger(target);
      var relativeStart = ES.ToInteger(start);
      var to = relativeTarget < 0 ? Math.max(len + relativeTarget, 0) : Math.min(relativeTarget, len);
      var from = relativeStart < 0 ? Math.max(len + relativeStart, 0) : Math.min(relativeStart, len);
      end = typeof end === 'undefined' ? len : ES.ToInteger(end);
      var fin = end < 0 ? Math.max(len + end, 0) : Math.min(end, len);
      var count = Math.min(fin - from, len - to);
      var direction = 1;
      if (from < to && to < (from + count)) {
        direction = -1;
        from += count - 1;
        to += count - 1;
      }
      while (count > 0) {
        if (_hasOwnProperty(o, from)) {
          o[to] = o[from];
        } else {
          delete o[from];
        }
        from += direction;
        to += direction;
        count -= 1;
      }
      return o;
    },

    fill: function fill(value) {
      var start = arguments.length > 1 ? arguments[1] : void 0;
      var end = arguments.length > 2 ? arguments[2] : void 0;
      var O = ES.ToObject(this);
      var len = ES.ToLength(O.length);
      start = ES.ToInteger(typeof start === 'undefined' ? 0 : start);
      end = ES.ToInteger(typeof end === 'undefined' ? len : end);

      var relativeStart = start < 0 ? Math.max(len + start, 0) : Math.min(start, len);
      var relativeEnd = end < 0 ? len + end : end;

      for (var i = relativeStart; i < len && i < relativeEnd; ++i) {
        O[i] = value;
      }
      return O;
    },

    find: function find(predicate) {
      var list = ES.ToObject(this);
      var length = ES.ToLength(list.length);
      if (!ES.IsCallable(predicate)) {
        throw new TypeError('Array#find: predicate must be a function');
      }
      var thisArg = arguments.length > 1 ? arguments[1] : null;
      for (var i = 0, value; i < length; i++) {
        value = list[i];
        if (thisArg) {
          if (predicate.call(thisArg, value, i, list)) { return value; }
        } else if (predicate(value, i, list)) {
          return value;
        }
      }
    },

    findIndex: function findIndex(predicate) {
      var list = ES.ToObject(this);
      var length = ES.ToLength(list.length);
      if (!ES.IsCallable(predicate)) {
        throw new TypeError('Array#findIndex: predicate must be a function');
      }
      var thisArg = arguments.length > 1 ? arguments[1] : null;
      for (var i = 0; i < length; i++) {
        if (thisArg) {
          if (predicate.call(thisArg, list[i], i, list)) { return i; }
        } else if (predicate(list[i], i, list)) {
          return i;
        }
      }
      return -1;
    },

    keys: function keys() {
      return new ArrayIterator(this, 'key');
    },

    values: function values() {
      return new ArrayIterator(this, 'value');
    },

    entries: function entries() {
      return new ArrayIterator(this, 'entry');
    }
  };
  // Safari 7.1 defines Array#keys and Array#entries natively,
  // but the resulting ArrayIterator objects don't have a "next" method.
  if (Array.prototype.keys && !ES.IsCallable([1].keys().next)) {
    delete Array.prototype.keys;
  }
  if (Array.prototype.entries && !ES.IsCallable([1].entries().next)) {
    delete Array.prototype.entries;
  }

  // Chrome 38 defines Array#keys and Array#entries, and Array#@@iterator, but not Array#values
  if (Array.prototype.keys && Array.prototype.entries && !Array.prototype.values && Array.prototype[$iterator$]) {
    defineProperties(Array.prototype, {
      values: Array.prototype[$iterator$]
    });
    if (Type.symbol(Symbol.unscopables)) {
      Array.prototype[Symbol.unscopables].values = true;
    }
  }
  // Chrome 40 defines Array#values with the incorrect name, although Array#{keys,entries} have the correct name
  if (Array.prototype.values && Array.prototype.values.name !== 'values') {
    var originalArrayPrototypeValues = Array.prototype.values;
    overrideNative(Array.prototype, 'values', function values() { return originalArrayPrototypeValues.call(this); });
    defineProperty(Array.prototype, $iterator$, Array.prototype.values, true);
  }
  defineProperties(Array.prototype, ArrayPrototypeShims);

  addIterator(Array.prototype, function () { return this.values(); });
  // Chrome defines keys/values/entries on Array, but doesn't give us
  // any way to identify its iterator.  So add our own shimmed field.
  if (Object.getPrototypeOf) {
    addIterator(Object.getPrototypeOf([].values()));
  }

  // note: this is positioned here because it relies on Array#entries
  var arrayFromSwallowsNegativeLengths = (function () {
    // Detects a Firefox bug in v32
    // https://bugzilla.mozilla.org/show_bug.cgi?id=1063993
    return valueOrFalseIfThrows(function () { return Array.from({ length: -1 }).length === 0; });
  }());
  var arrayFromHandlesIterables = (function () {
    // Detects a bug in Webkit nightly r181886
    var arr = Array.from([0].entries());
    return arr.length === 1 && arr[0][0] === 0 && arr[0][1] === 1;
  }());
  if (!arrayFromSwallowsNegativeLengths || !arrayFromHandlesIterables) {
    overrideNative(Array, 'from', ArrayShims.from);
  }

  var maxSafeInteger = Math.pow(2, 53) - 1;
  defineProperties(Number, {
    MAX_SAFE_INTEGER: maxSafeInteger,
    MIN_SAFE_INTEGER: -maxSafeInteger,
    EPSILON: 2.220446049250313e-16,

    parseInt: globals.parseInt,
    parseFloat: globals.parseFloat,

    isFinite: numberIsFinite,

    isInteger: function isInteger(value) {
      return numberIsFinite(value) && ES.ToInteger(value) === value;
    },

    isSafeInteger: function isSafeInteger(value) {
      return Number.isInteger(value) && Math.abs(value) <= Number.MAX_SAFE_INTEGER;
    },

    isNaN: numberIsNaN
  });
  // Firefox 37 has a conforming Number.parseInt, but it's not === to the global parseInt (fixed in v40)
  defineProperty(Number, 'parseInt', globals.parseInt, Number.parseInt !== globals.parseInt);

  // Work around bugs in Array#find and Array#findIndex -- early
  // implementations skipped holes in sparse arrays. (Note that the
  // implementations of find/findIndex indirectly use shimmed
  // methods of Number, so this test has to happen down here.)
  /*jshint elision: true */
  if (![, 1].find(function (item, idx) { return idx === 0; })) {
    overrideNative(Array.prototype, 'find', ArrayPrototypeShims.find);
  }
  if ([, 1].findIndex(function (item, idx) { return idx === 0; }) !== 0) {
    overrideNative(Array.prototype, 'findIndex', ArrayPrototypeShims.findIndex);
  }
  /*jshint elision: false */

  var isEnumerableOn = Function.bind.call(Function.bind, Object.prototype.propertyIsEnumerable);
  var sliceArgs = function sliceArgs() {
    // per https://github.com/petkaantonov/bluebird/wiki/Optimization-killers#32-leaking-arguments
    // and https://gist.github.com/WebReflection/4327762cb87a8c634a29
    var initial = Number(this);
    var len = arguments.length;
    var desiredArgCount = len - initial;
    var args = new Array(desiredArgCount < 0 ? 0 : desiredArgCount);
    for (var i = initial; i < len; ++i) {
      args[i - initial] = arguments[i];
    }
    return args;
  };
  var assignTo = function assignTo(source) {
    return function assignToSource(target, key) {
      target[key] = source[key];
      return target;
    };
  };
  var assignReducer = function (target, source) {
    var keys = Object.keys(Object(source));
    var symbols;
    if (ES.IsCallable(Object.getOwnPropertySymbols)) {
      symbols = Object.getOwnPropertySymbols(Object(source)).filter(isEnumerableOn(source));
    }
    return keys.concat(symbols || []).reduce(assignTo(source), target);
  };

  var ObjectShims = {
    // 19.1.3.1
    assign: function (target, source) {
      if (!ES.TypeIsObject(target)) {
        throw new TypeError('target must be an object');
      }
      return Array.prototype.reduce.call(sliceArgs.apply(0, arguments), assignReducer);
    },

    // Added in WebKit in https://bugs.webkit.org/show_bug.cgi?id=143865
    is: function is(a, b) {
      return ES.SameValue(a, b);
    }
  };
  var assignHasPendingExceptions = Object.assign && Object.preventExtensions && (function () {
    // Firefox 37 still has "pending exception" logic in its Object.assign implementation,
    // which is 72% slower than our shim, and Firefox 40's native implementation.
    var thrower = Object.preventExtensions({ 1: 2 });
    try {
      Object.assign(thrower, 'xy');
    } catch (e) {
      return thrower[1] === 'y';
    }
  }());
  if (assignHasPendingExceptions) {
    overrideNative(Object, 'assign', ObjectShims.assign);
  }
  defineProperties(Object, ObjectShims);

  if (supportsDescriptors) {
    var ES5ObjectShims = {
      // 19.1.3.9
      // shim from https://gist.github.com/WebReflection/5593554
      setPrototypeOf: (function (Object, magic) {
        var set;

        var checkArgs = function (O, proto) {
          if (!ES.TypeIsObject(O)) {
            throw new TypeError('cannot set prototype on a non-object');
          }
          if (!(proto === null || ES.TypeIsObject(proto))) {
            throw new TypeError('can only set prototype to an object or null' + proto);
          }
        };

        var setPrototypeOf = function (O, proto) {
          checkArgs(O, proto);
          set.call(O, proto);
          return O;
        };

        try {
          // this works already in Firefox and Safari
          set = Object.getOwnPropertyDescriptor(Object.prototype, magic).set;
          set.call({}, null);
        } catch (e) {
          if (Object.prototype !== {}[magic]) {
            // IE < 11 cannot be shimmed
            return;
          }
          // probably Chrome or some old Mobile stock browser
          set = function (proto) {
            this[magic] = proto;
          };
          // please note that this will **not** work
          // in those browsers that do not inherit
          // __proto__ by mistake from Object.prototype
          // in these cases we should probably throw an error
          // or at least be informed about the issue
          setPrototypeOf.polyfill = setPrototypeOf(
            setPrototypeOf({}, null),
            Object.prototype
          ) instanceof Object;
          // setPrototypeOf.polyfill === true means it works as meant
          // setPrototypeOf.polyfill === false means it's not 100% reliable
          // setPrototypeOf.polyfill === undefined
          // or
          // setPrototypeOf.polyfill ==  null means it's not a polyfill
          // which means it works as expected
          // we can even delete Object.prototype.__proto__;
        }
        return setPrototypeOf;
      }(Object, '__proto__'))
    };

    defineProperties(Object, ES5ObjectShims);
  }

  // Workaround bug in Opera 12 where setPrototypeOf(x, null) doesn't work,
  // but Object.create(null) does.
  if (Object.setPrototypeOf && Object.getPrototypeOf &&
      Object.getPrototypeOf(Object.setPrototypeOf({}, null)) !== null &&
      Object.getPrototypeOf(Object.create(null)) === null) {
    (function () {
      var FAKENULL = Object.create(null);
      var gpo = Object.getPrototypeOf, spo = Object.setPrototypeOf;
      Object.getPrototypeOf = function (o) {
        var result = gpo(o);
        return result === FAKENULL ? null : result;
      };
      Object.setPrototypeOf = function (o, p) {
        var proto = p === null ? FAKENULL : p;
        return spo(o, proto);
      };
      Object.setPrototypeOf.polyfill = false;
    }());
  }

  var objectKeysAcceptsPrimitives = !throwsError(function () { Object.keys('foo'); });
  if (!objectKeysAcceptsPrimitives) {
    var originalObjectKeys = Object.keys;
    overrideNative(Object, 'keys', function keys(value) {
      return originalObjectKeys(ES.ToObject(value));
    });
  }

  if (Object.getOwnPropertyNames) {
    var objectGOPNAcceptsPrimitives = !throwsError(function () { Object.getOwnPropertyNames('foo'); });
    if (!objectGOPNAcceptsPrimitives) {
      var originalObjectGetOwnPropertyNames = Object.getOwnPropertyNames;
      overrideNative(Object, 'getOwnPropertyNames', function getOwnPropertyNames(value) {
        return originalObjectGetOwnPropertyNames(ES.ToObject(value));
      });
    }
  }
  if (Object.getOwnPropertyDescriptor) {
    var objectGOPDAcceptsPrimitives = !throwsError(function () { Object.getOwnPropertyDescriptor('foo', 'bar'); });
    if (!objectGOPDAcceptsPrimitives) {
      var originalObjectGetOwnPropertyDescriptor = Object.getOwnPropertyDescriptor;
      overrideNative(Object, 'getOwnPropertyDescriptor', function getOwnPropertyDescriptor(value, property) {
        return originalObjectGetOwnPropertyDescriptor(ES.ToObject(value), property);
      });
    }
  }
  if (Object.seal) {
    var objectSealAcceptsPrimitives = !throwsError(function () { Object.seal('foo'); });
    if (!objectSealAcceptsPrimitives) {
      var originalObjectSeal = Object.seal;
      overrideNative(Object, 'seal', function seal(value) {
        if (!Type.object(value)) { return value; }
        return originalObjectSeal(value);
      });
    }
  }
  if (Object.isSealed) {
    var objectIsSealedAcceptsPrimitives = !throwsError(function () { Object.isSealed('foo'); });
    if (!objectIsSealedAcceptsPrimitives) {
      var originalObjectIsSealed = Object.isSealed;
      overrideNative(Object, 'isSealed', function isSealed(value) {
        if (!Type.object(value)) { return true; }
        return originalObjectIsSealed(value);
      });
    }
  }
  if (Object.freeze) {
    var objectFreezeAcceptsPrimitives = !throwsError(function () { Object.freeze('foo'); });
    if (!objectFreezeAcceptsPrimitives) {
      var originalObjectFreeze = Object.freeze;
      overrideNative(Object, 'freeze', function freeze(value) {
        if (!Type.object(value)) { return value; }
        return originalObjectFreeze(value);
      });
    }
  }
  if (Object.isFrozen) {
    var objectIsFrozenAcceptsPrimitives = !throwsError(function () { Object.isFrozen('foo'); });
    if (!objectIsFrozenAcceptsPrimitives) {
      var originalObjectIsFrozen = Object.isFrozen;
      overrideNative(Object, 'isFrozen', function isFrozen(value) {
        if (!Type.object(value)) { return true; }
        return originalObjectIsFrozen(value);
      });
    }
  }
  if (Object.preventExtensions) {
    var objectPreventExtensionsAcceptsPrimitives = !throwsError(function () { Object.preventExtensions('foo'); });
    if (!objectPreventExtensionsAcceptsPrimitives) {
      var originalObjectPreventExtensions = Object.preventExtensions;
      overrideNative(Object, 'preventExtensions', function preventExtensions(value) {
        if (!Type.object(value)) { return value; }
        return originalObjectPreventExtensions(value);
      });
    }
  }
  if (Object.isExtensible) {
    var objectIsExtensibleAcceptsPrimitives = !throwsError(function () { Object.isExtensible('foo'); });
    if (!objectIsExtensibleAcceptsPrimitives) {
      var originalObjectIsExtensible = Object.isExtensible;
      overrideNative(Object, 'isExtensible', function isExtensible(value) {
        if (!Type.object(value)) { return false; }
        return originalObjectIsExtensible(value);
      });
    }
  }
  if (Object.getPrototypeOf) {
    var objectGetProtoAcceptsPrimitives = !throwsError(function () { Object.getPrototypeOf('foo'); });
    if (!objectGetProtoAcceptsPrimitives) {
      var originalGetProto = Object.getPrototypeOf;
      overrideNative(Object, 'getPrototypeOf', function getPrototypeOf(value) {
        return originalGetProto(ES.ToObject(value));
      });
    }
  }

  if (!RegExp.prototype.flags && supportsDescriptors) {
    var regExpFlagsGetter = function flags() {
      if (!ES.TypeIsObject(this)) {
        throw new TypeError('Method called on incompatible type: must be an object.');
      }
      var result = '';
      if (this.global) {
        result += 'g';
      }
      if (this.ignoreCase) {
        result += 'i';
      }
      if (this.multiline) {
        result += 'm';
      }
      if (this.unicode) {
        result += 'u';
      }
      if (this.sticky) {
        result += 'y';
      }
      return result;
    };

    Value.getter(RegExp.prototype, 'flags', regExpFlagsGetter);
  }

  var regExpSupportsFlagsWithRegex = valueOrFalseIfThrows(function () {
    return String(new RegExp(/a/g, 'i')) === '/a/i';
  });

  if (!regExpSupportsFlagsWithRegex && supportsDescriptors) {
    var OrigRegExp = RegExp;
    var RegExpShim = function RegExp(pattern, flags) {
      if (Type.regex(pattern) && Type.string(flags)) {
        return new RegExp(pattern.source, flags);
      }
      return new OrigRegExp(pattern, flags);
    };
    Value.preserveToString(RegExpShim, OrigRegExp);
    if (Object.setPrototypeOf) {
      // sets up proper prototype chain where possible
      Object.setPrototypeOf(OrigRegExp, RegExpShim);
    }
    Object.getOwnPropertyNames(OrigRegExp).forEach(function (key) {
      if (key === '$input') { return; } // Chrome < v39 & Opera < 26 have a nonstandard "$input" property
      if (key in noop) { return; }
      Value.proxy(OrigRegExp, key, RegExpShim);
    });
    RegExpShim.prototype = OrigRegExp.prototype;
    Value.redefine(OrigRegExp.prototype, 'constructor', RegExpShim);
    /*globals RegExp: true */
    RegExp = RegExpShim;
    Value.redefine(globals, 'RegExp', RegExpShim);
    /*globals RegExp: false */
  }

  if (supportsDescriptors) {
    var regexGlobals = {
      input: '$_',
      lastMatch: '$&',
      lastParen: '$+',
      leftContext: '$`',
      rightContext: '$\''
    };
    Object.keys(regexGlobals).forEach(function (prop) {
      if (prop in RegExp && !(regexGlobals[prop] in RegExp)) {
        Value.getter(RegExp, regexGlobals[prop], function get() {
          return RegExp[prop];
        });
      }
    });
  }

  var square = function (n) { return n * n; };
  var add = function (a, b) { return a + b; };
  var inverseEpsilon = 1 / Number.EPSILON;
  var roundTiesToEven = function roundTiesToEven(n) {
    // Even though this reduces down to `return n`, it takes advantage of built-in rounding.
    return (n + inverseEpsilon) - inverseEpsilon;
  };
  var BINARY_32_EPSILON = Math.pow(2, -23);
  var BINARY_32_MAX_VALUE = Math.pow(2, 127) * (2 - BINARY_32_EPSILON);
  var BINARY_32_MIN_VALUE = Math.pow(2, -126);

  var MathShims = {
    acosh: function acosh(value) {
      var x = Number(value);
      if (Number.isNaN(x) || value < 1) { return NaN; }
      if (x === 1) { return 0; }
      if (x === Infinity) { return x; }
      return Math.log(x / Math.E + Math.sqrt(x + 1) * Math.sqrt(x - 1) / Math.E) + 1;
    },

    asinh: function asinh(value) {
      var x = Number(value);
      if (x === 0 || !globalIsFinite(x)) {
        return x;
      }
      return x < 0 ? -Math.asinh(-x) : Math.log(x + Math.sqrt(x * x + 1));
    },

    atanh: function atanh(value) {
      var x = Number(value);
      if (Number.isNaN(x) || x < -1 || x > 1) {
        return NaN;
      }
      if (x === -1) { return -Infinity; }
      if (x === 1) { return Infinity; }
      if (x === 0) { return x; }
      return 0.5 * Math.log((1 + x) / (1 - x));
    },

    cbrt: function cbrt(value) {
      var x = Number(value);
      if (x === 0) { return x; }
      var negate = x < 0, result;
      if (negate) { x = -x; }
      if (x === Infinity) {
        result = Infinity;
      } else {
        result = Math.exp(Math.log(x) / 3);
        // from http://en.wikipedia.org/wiki/Cube_root#Numerical_methods
        result = (x / (result * result) + (2 * result)) / 3;
      }
      return negate ? -result : result;
    },

    clz32: function clz32(value) {
      // See https://bugs.ecmascript.org/show_bug.cgi?id=2465
      var x = Number(value);
      var number = ES.ToUint32(x);
      if (number === 0) {
        return 32;
      }
      return 31 - Math.floor(Math.log(number + 0.5) * Math.LOG2E);
    },

    cosh: function cosh(value) {
      var x = Number(value);
      if (x === 0) { return 1; } // +0 or -0
      if (Number.isNaN(x)) { return NaN; }
      if (!globalIsFinite(x)) { return Infinity; }
      if (x < 0) { x = -x; }
      if (x > 21) { return Math.exp(x) / 2; }
      return (Math.exp(x) + Math.exp(-x)) / 2;
    },

    expm1: function expm1(value) {
      var x = Number(value);
      if (x === -Infinity) { return -1; }
      if (!globalIsFinite(x) || x === 0) { return x; }
      if (Math.abs(x) > 0.5) {
        return Math.exp(x) - 1;
      }
      // A more precise approximation using Taylor series expansion
      // from https://github.com/paulmillr/es6-shim/issues/314#issuecomment-70293986
      var t = x;
      var sum = 0;
      var n = 1;
      while (sum + t !== sum) {
        sum += t;
        n += 1;
        t *= x / n;
      }
      return sum;
    },

    hypot: function hypot(x, y) {
      var anyNaN = false;
      var allZero = true;
      var anyInfinity = false;
      var numbers = [];
      Array.prototype.every.call(arguments, function (arg) {
        var num = Number(arg);
        if (Number.isNaN(num)) {
          anyNaN = true;
        } else if (num === Infinity || num === -Infinity) {
          anyInfinity = true;
        } else if (num !== 0) {
          allZero = false;
        }
        if (anyInfinity) {
          return false;
        } else if (!anyNaN) {
          numbers.push(Math.abs(num));
        }
        return true;
      });
      if (anyInfinity) { return Infinity; }
      if (anyNaN) { return NaN; }
      if (allZero) { return 0; }

      var largest = Math.max.apply(Math, numbers);
      var divided = numbers.map(function (number) { return number / largest; });
      var sum = divided.map(square).reduce(add);
      return largest * Math.sqrt(sum);
    },

    log2: function log2(value) {
      return Math.log(value) * Math.LOG2E;
    },

    log10: function log10(value) {
      return Math.log(value) * Math.LOG10E;
    },

    log1p: function log1p(value) {
      var x = Number(value);
      if (x < -1 || Number.isNaN(x)) { return NaN; }
      if (x === 0 || x === Infinity) { return x; }
      if (x === -1) { return -Infinity; }

      return (1 + x) - 1 === 0 ? x : x * (Math.log(1 + x) / ((1 + x) - 1));
    },

    sign: function sign(value) {
      var number = Number(value);
      if (number === 0) { return number; }
      if (Number.isNaN(number)) { return number; }
      return number < 0 ? -1 : 1;
    },

    sinh: function sinh(value) {
      var x = Number(value);
      if (!globalIsFinite(x) || x === 0) { return x; }

      if (Math.abs(x) < 1) {
        return (Math.expm1(x) - Math.expm1(-x)) / 2;
      }
      return (Math.exp(x - 1) - Math.exp(-x - 1)) * Math.E / 2;
    },

    tanh: function tanh(value) {
      var x = Number(value);
      if (Number.isNaN(x) || x === 0) { return x; }
      if (x === Infinity) { return 1; }
      if (x === -Infinity) { return -1; }
      var a = Math.expm1(x);
      var b = Math.expm1(-x);
      if (a === Infinity) { return 1; }
      if (b === Infinity) { return -1; }
      return (a - b) / (Math.exp(x) + Math.exp(-x));
    },

    trunc: function trunc(value) {
      var x = Number(value);
      return x < 0 ? -Math.floor(-x) : Math.floor(x);
    },

    imul: function imul(x, y) {
      // taken from https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/imul
      var a = ES.ToUint32(x);
      var b = ES.ToUint32(y);
      var ah = (a >>> 16) & 0xffff;
      var al = a & 0xffff;
      var bh = (b >>> 16) & 0xffff;
      var bl = b & 0xffff;
      // the shift by 0 fixes the sign on the high part
      // the final |0 converts the unsigned value into a signed value
      return ((al * bl) + (((ah * bl + al * bh) << 16) >>> 0) | 0);
    },

    fround: function fround(x) {
      var v = Number(x);
      if (v === 0 || v === Infinity || v === -Infinity || numberIsNaN(v)) {
        return v;
      }
      var sign = Math.sign(v);
      var abs = Math.abs(v);
      if (abs < BINARY_32_MIN_VALUE) {
        return sign * roundTiesToEven(abs / BINARY_32_MIN_VALUE / BINARY_32_EPSILON) * BINARY_32_MIN_VALUE * BINARY_32_EPSILON;
      }
      // Veltkamp's splitting (?)
      var a = (1 + BINARY_32_EPSILON / Number.EPSILON) * abs;
      var result = a - (a - abs);
      if (result > BINARY_32_MAX_VALUE || numberIsNaN(result)) {
        return sign * Infinity;
      }
      return sign * result;
    }
  };
  defineProperties(Math, MathShims);
  // IE 11 TP has an imprecise log1p: reports Math.log1p(-1e-17) as 0
  defineProperty(Math, 'log1p', MathShims.log1p, Math.log1p(-1e-17) !== -1e-17);
  // IE 11 TP has an imprecise asinh: reports Math.asinh(-1e7) as not exactly equal to -Math.asinh(1e7)
  defineProperty(Math, 'asinh', MathShims.asinh, Math.asinh(-1e7) !== -Math.asinh(1e7));
  // Chrome 40 has an imprecise Math.tanh with very small numbers
  defineProperty(Math, 'tanh', MathShims.tanh, Math.tanh(-2e-17) !== -2e-17);
  // Chrome 40 loses Math.acosh precision with high numbers
  defineProperty(Math, 'acosh', MathShims.acosh, Math.acosh(Number.MAX_VALUE) === Infinity);
  // Firefox 38 on Windows
  defineProperty(Math, 'cbrt', MathShims.cbrt, Math.abs(1 - Math.cbrt(1e-300) / 1e-100) / Number.EPSILON > 8);
  // node 0.11 has an imprecise Math.sinh with very small numbers
  defineProperty(Math, 'sinh', MathShims.sinh, Math.sinh(-2e-17) !== -2e-17);
  // FF 35 on Linux reports 22025.465794806725 for Math.expm1(10)
  var expm1OfTen = Math.expm1(10);
  defineProperty(Math, 'expm1', MathShims.expm1, expm1OfTen > 22025.465794806719 || expm1OfTen < 22025.4657948067165168);

  var origMathRound = Math.round;
  // breaks in e.g. Safari 8, Internet Explorer 11, Opera 12
  var roundHandlesBoundaryConditions = Math.round(0.5 - Number.EPSILON / 4) === 0 && Math.round(-0.5 + Number.EPSILON / 3.99) === 1;

  // When engines use Math.floor(x + 0.5) internally, Math.round can be buggy for large integers.
  // This behavior should be governed by "round to nearest, ties to even mode"
  // see https://people.mozilla.org/~jorendorff/es6-draft.html#sec-ecmascript-language-types-number-type
  // These are the boundary cases where it breaks.
  var smallestPositiveNumberWhereRoundBreaks = inverseEpsilon + 1;
  var largestPositiveNumberWhereRoundBreaks = 2 * inverseEpsilon - 1;
  var roundDoesNotIncreaseIntegers = [smallestPositiveNumberWhereRoundBreaks, largestPositiveNumberWhereRoundBreaks].every(function (num) {
    return Math.round(num) === num;
  });
  defineProperty(Math, 'round', function round(x) {
    var floor = Math.floor(x);
    var ceil = floor === -1 ? -0 : floor + 1;
    return x - floor < 0.5 ? floor : ceil;
  }, !roundHandlesBoundaryConditions || !roundDoesNotIncreaseIntegers);
  Value.preserveToString(Math.round, origMathRound);

  var origImul = Math.imul;
  if (Math.imul(0xffffffff, 5) !== -5) {
    // Safari 6.1, at least, reports "0" for this value
    Math.imul = MathShims.imul;
    Value.preserveToString(Math.imul, origImul);
  }
  if (Math.imul.length !== 2) {
    // Safari 8.0.4 has a length of 1
    // fixed in https://bugs.webkit.org/show_bug.cgi?id=143658
    overrideNative(Math, 'imul', function imul(x, y) {
      return origImul.apply(Math, arguments);
    });
  }

  // Promises
  // Simplest possible implementation; use a 3rd-party library if you
  // want the best possible speed and/or long stack traces.
  var PromiseShim = (function () {

    var Promise, Promise$prototype;

    ES.IsPromise = function (promise) {
      if (!ES.TypeIsObject(promise)) {
        return false;
      }
      if (!promise._promiseConstructor) {
        // _promiseConstructor is a bit more unique than _status, so we'll
        // check that instead of the [[PromiseStatus]] internal field.
        return false;
      }
      if (typeof promise._status === 'undefined') {
        return false; // uninitialized
      }
      return true;
    };

    // "PromiseCapability" in the spec is what most promise implementations
    // call a "deferred".
    var PromiseCapability = function (C) {
      if (!ES.IsCallable(C)) {
        throw new TypeError('bad promise constructor');
      }
      var capability = this;
      var resolver = function (resolve, reject) {
        capability.resolve = resolve;
        capability.reject = reject;
      };
      capability.promise = ES.Construct(C, [resolver]);
      // see https://bugs.ecmascript.org/show_bug.cgi?id=2478
      if (!capability.promise._es6construct) {
        throw new TypeError('bad promise constructor');
      }
      if (!(ES.IsCallable(capability.resolve) && ES.IsCallable(capability.reject))) {
        throw new TypeError('bad promise constructor');
      }
    };

    // find an appropriate setImmediate-alike
    var setTimeout = globals.setTimeout;
    var makeZeroTimeout;
    /*global window */
    if (typeof window !== 'undefined' && ES.IsCallable(window.postMessage)) {
      makeZeroTimeout = function () {
        // from http://dbaron.org/log/20100309-faster-timeouts
        var timeouts = [];
        var messageName = 'zero-timeout-message';
        var setZeroTimeout = function (fn) {
          timeouts.push(fn);
          window.postMessage(messageName, '*');
        };
        var handleMessage = function (event) {
          if (event.source === window && event.data === messageName) {
            event.stopPropagation();
            if (timeouts.length === 0) { return; }
            var fn = timeouts.shift();
            fn();
          }
        };
        window.addEventListener('message', handleMessage, true);
        return setZeroTimeout;
      };
    }
    var makePromiseAsap = function () {
      // An efficient task-scheduler based on a pre-existing Promise
      // implementation, which we can use even if we override the
      // global Promise below (in order to workaround bugs)
      // https://github.com/Raynos/observ-hash/issues/2#issuecomment-35857671
      var P = globals.Promise;
      return P && P.resolve && function (task) {
        return P.resolve().then(task);
      };
    };
    /*global process */
    var enqueue = ES.IsCallable(globals.setImmediate) ?
      globals.setImmediate.bind(globals) :
      typeof process === 'object' && process.nextTick ? process.nextTick :
      makePromiseAsap() ||
      (ES.IsCallable(makeZeroTimeout) ? makeZeroTimeout() :
      function (task) { setTimeout(task, 0); }); // fallback

    var updatePromiseFromPotentialThenable = function (x, capability) {
      if (!ES.TypeIsObject(x)) {
        return false;
      }
      var resolve = capability.resolve;
      var reject = capability.reject;
      try {
        var then = x.then; // only one invocation of accessor
        if (!ES.IsCallable(then)) { return false; }
        then.call(x, resolve, reject);
      } catch (e) {
        reject(e);
      }
      return true;
    };

    var triggerPromiseReactions = function (reactions, x) {
      reactions.forEach(function (reaction) {
        enqueue(function () {
          // PromiseReactionTask
          var handler = reaction.handler;
          var capability = reaction.capability;
          var resolve = capability.resolve;
          var reject = capability.reject;
          try {
            var result = handler(x);
            if (result === capability.promise) {
              throw new TypeError('self resolution');
            }
            var updateResult =
              updatePromiseFromPotentialThenable(result, capability);
            if (!updateResult) {
              resolve(result);
            }
          } catch (e) {
            reject(e);
          }
        });
      });
    };

    var promiseResolutionHandler = function (promise, onFulfilled, onRejected) {
      return function (x) {
        if (x === promise) {
          return onRejected(new TypeError('self resolution'));
        }
        var C = promise._promiseConstructor;
        var capability = new PromiseCapability(C);
        var updateResult = updatePromiseFromPotentialThenable(x, capability);
        if (updateResult) {
          return capability.promise.then(onFulfilled, onRejected);
        } else {
          return onFulfilled(x);
        }
      };
    };

    Promise = function (resolver) {
      var promise = this;
      promise = emulateES6construct(promise);
      if (!promise._promiseConstructor) {
        // we use _promiseConstructor as a stand-in for the internal
        // [[PromiseStatus]] field; it's a little more unique.
        throw new TypeError('bad promise');
      }
      if (typeof promise._status !== 'undefined') {
        throw new TypeError('promise already initialized');
      }
      // see https://bugs.ecmascript.org/show_bug.cgi?id=2482
      if (!ES.IsCallable(resolver)) {
        throw new TypeError('not a valid resolver');
      }
      promise._status = 'unresolved';
      promise._resolveReactions = [];
      promise._rejectReactions = [];

      var resolve = function (resolution) {
        if (promise._status !== 'unresolved') { return; }
        var reactions = promise._resolveReactions;
        promise._result = resolution;
        promise._resolveReactions = void 0;
        promise._rejectReactions = void 0;
        promise._status = 'has-resolution';
        triggerPromiseReactions(reactions, resolution);
      };
      var reject = function (reason) {
        if (promise._status !== 'unresolved') { return; }
        var reactions = promise._rejectReactions;
        promise._result = reason;
        promise._resolveReactions = void 0;
        promise._rejectReactions = void 0;
        promise._status = 'has-rejection';
        triggerPromiseReactions(reactions, reason);
      };
      try {
        resolver(resolve, reject);
      } catch (e) {
        reject(e);
      }
      return promise;
    };
    Promise$prototype = Promise.prototype;
    var _promiseAllResolver = function (index, values, capability, remaining) {
      var done = false;
      return function (x) {
        if (done) { return; } // protect against being called multiple times
        done = true;
        values[index] = x;
        if ((--remaining.count) === 0) {
          var resolve = capability.resolve;
          resolve(values); // call w/ this===undefined
        }
      };
    };

    defineProperty(Promise, symbolSpecies, function (obj) {
      var constructor = this;
      // AllocatePromise
      // The `obj` parameter is a hack we use for es5
      // compatibility.
      var prototype = constructor.prototype || Promise$prototype;
      var object = obj || create(prototype);
      defineProperties(object, {
        _status: void 0,
        _result: void 0,
        _resolveReactions: void 0,
        _rejectReactions: void 0,
        _promiseConstructor: void 0
      });
      object._promiseConstructor = constructor;
      return object;
    });
    defineProperties(Promise, {
      all: function all(iterable) {
        var C = this;
        var capability = new PromiseCapability(C);
        var resolve = capability.resolve;
        var reject = capability.reject;
        try {
          if (!ES.IsIterable(iterable)) {
            throw new TypeError('bad iterable');
          }
          var it = ES.GetIterator(iterable);
          var values = [], remaining = { count: 1 };
          for (var index = 0; ; index++) {
            var next = ES.IteratorNext(it);
            if (next.done) {
              break;
            }
            var nextPromise = C.resolve(next.value);
            var resolveElement = _promiseAllResolver(
              index, values, capability, remaining
            );
            remaining.count++;
            nextPromise.then(resolveElement, capability.reject);
          }
          if ((--remaining.count) === 0) {
            resolve(values); // call w/ this===undefined
          }
        } catch (e) {
          reject(e);
        }
        return capability.promise;
      },

      race: function race(iterable) {
        var C = this;
        var capability = new PromiseCapability(C);
        var resolve = capability.resolve;
        var reject = capability.reject;
        try {
          if (!ES.IsIterable(iterable)) {
            throw new TypeError('bad iterable');
          }
          var it = ES.GetIterator(iterable);
          while (true) {
            var next = ES.IteratorNext(it);
            if (next.done) {
              // If iterable has no items, resulting promise will never
              // resolve; see:
              // https://github.com/domenic/promises-unwrapping/issues/75
              // https://bugs.ecmascript.org/show_bug.cgi?id=2515
              break;
            }
            var nextPromise = C.resolve(next.value);
            nextPromise.then(resolve, reject);
          }
        } catch (e) {
          reject(e);
        }
        return capability.promise;
      },

      reject: function reject(reason) {
        var C = this;
        var capability = new PromiseCapability(C);
        var rejectPromise = capability.reject;
        rejectPromise(reason); // call with this===undefined
        return capability.promise;
      },

      resolve: function resolve(v) {
        var C = this;
        if (ES.IsPromise(v)) {
          var constructor = v._promiseConstructor;
          if (constructor === C) { return v; }
        }
        var capability = new PromiseCapability(C);
        var resolvePromise = capability.resolve;
        resolvePromise(v); // call with this===undefined
        return capability.promise;
      }
    });

    var Identity = function (x) { return x; };
    var Thrower = function (e) { throw e; };

    defineProperties(Promise$prototype, {
      'catch': function (onRejected) {
        return this.then(void 0, onRejected);
      },

      then: function then(onFulfilled, onRejected) {
        var promise = this;
        if (!ES.IsPromise(promise)) { throw new TypeError('not a promise'); }
        // this.constructor not this._promiseConstructor; see
        // https://bugs.ecmascript.org/show_bug.cgi?id=2513
        var C = this.constructor;
        var capability = new PromiseCapability(C);
        if (!ES.IsCallable(onRejected)) {
          onRejected = Thrower;
        }
        if (!ES.IsCallable(onFulfilled)) {
          onFulfilled = Identity;
        }
        var resolutionHandler = promiseResolutionHandler(promise, onFulfilled, onRejected);
        var resolveReaction = { capability: capability, handler: resolutionHandler };
        var rejectReaction = { capability: capability, handler: onRejected };
        switch (promise._status) {
          case 'unresolved':
            promise._resolveReactions.push(resolveReaction);
            promise._rejectReactions.push(rejectReaction);
            break;
          case 'has-resolution':
            triggerPromiseReactions([resolveReaction], promise._result);
            break;
          case 'has-rejection':
            triggerPromiseReactions([rejectReaction], promise._result);
            break;
          default:
            throw new TypeError('unexpected');
        }
        return capability.promise;
      }
    });

    return Promise;
  }());

  // Chrome's native Promise has extra methods that it shouldn't have. Let's remove them.
  if (globals.Promise) {
    delete globals.Promise.accept;
    delete globals.Promise.defer;
    delete globals.Promise.prototype.chain;
  }

  // export the Promise constructor.
  defineProperties(globals, { Promise: PromiseShim });
  // In Chrome 33 (and thereabouts) Promise is defined, but the
  // implementation is buggy in a number of ways.  Let's check subclassing
  // support to see if we have a buggy implementation.
  var promiseSupportsSubclassing = supportsSubclassing(globals.Promise, function (S) {
    return S.resolve(42) instanceof S;
  });
  var promiseIgnoresNonFunctionThenCallbacks = !throwsError(function () { globals.Promise.reject(42).then(null, 5).then(null, noop); });
  var promiseRequiresObjectContext = throwsError(function () { globals.Promise.call(3, noop); });
  if (!promiseSupportsSubclassing || !promiseIgnoresNonFunctionThenCallbacks || !promiseRequiresObjectContext) {
    /*globals Promise: true */
    Promise = PromiseShim;
    /*globals Promise: false */
    overrideNative(globals, 'Promise', PromiseShim);
  }

  // Map and Set require a true ES5 environment
  // Their fast path also requires that the environment preserve
  // property insertion order, which is not guaranteed by the spec.
  var testOrder = function (a) {
    var b = Object.keys(a.reduce(function (o, k) {
      o[k] = true;
      return o;
    }, {}));
    return a.join(':') === b.join(':');
  };
  var preservesInsertionOrder = testOrder(['z', 'a', 'bb']);
  // some engines (eg, Chrome) only preserve insertion order for string keys
  var preservesNumericInsertionOrder = testOrder(['z', 1, 'a', '3', 2]);

  if (supportsDescriptors) {

    var fastkey = function fastkey(key) {
      if (!preservesInsertionOrder) {
        return null;
      }
      var type = typeof key;
      if (type === 'string') {
        return '$' + key;
      } else if (type === 'number') {
        // note that -0 will get coerced to "0" when used as a property key
        if (!preservesNumericInsertionOrder) {
          return 'n' + key;
        }
        return key;
      }
      return null;
    };

    var emptyObject = function emptyObject() {
      // accomodate some older not-quite-ES5 browsers
      return Object.create ? Object.create(null) : {};
    };

    var collectionShims = {
      Map: (function () {

        var empty = {};

        function MapEntry(key, value) {
          this.key = key;
          this.value = value;
          this.next = null;
          this.prev = null;
        }

        MapEntry.prototype.isRemoved = function () {
          return this.key === empty;
        };

        function MapIterator(map, kind) {
          this.head = map._head;
          this.i = this.head;
          this.kind = kind;
        }

        MapIterator.prototype = {
          next: function () {
            var i = this.i, kind = this.kind, head = this.head, result;
            if (typeof this.i === 'undefined') {
              return { value: void 0, done: true };
            }
            while (i.isRemoved() && i !== head) {
              // back up off of removed entries
              i = i.prev;
            }
            // advance to next unreturned element.
            while (i.next !== head) {
              i = i.next;
              if (!i.isRemoved()) {
                if (kind === 'key') {
                  result = i.key;
                } else if (kind === 'value') {
                  result = i.value;
                } else {
                  result = [i.key, i.value];
                }
                this.i = i;
                return { value: result, done: false };
              }
            }
            // once the iterator is done, it is done forever.
            this.i = void 0;
            return { value: void 0, done: true };
          }
        };
        addIterator(MapIterator.prototype);

        function Map() {
          var map = this;
          if (!ES.TypeIsObject(map)) {
            throw new TypeError("Constructor Map requires 'new'");
          }
          map = emulateES6construct(map);
          if (!map._es6map) {
            throw new TypeError('bad map');
          }

          var head = new MapEntry(null, null);
          // circular doubly-linked list.
          head.next = head.prev = head;

          defineProperties(map, {
            _head: head,
            _storage: emptyObject(),
            _size: 0
          });

          // Optionally initialize map from iterable
          if (arguments.length > 0 && typeof arguments[0] !== 'undefined' && arguments[0] !== null) {
            var it = ES.GetIterator(arguments[0]);
            var adder = map.set;
            if (!ES.IsCallable(adder)) { throw new TypeError('bad map'); }
            while (true) {
              var next = ES.IteratorNext(it);
              if (next.done) { break; }
              var nextItem = next.value;
              if (!ES.TypeIsObject(nextItem)) {
                throw new TypeError('expected iterable of pairs');
              }
              adder.call(map, nextItem[0], nextItem[1]);
            }
          }
          return map;
        }
        var Map$prototype = Map.prototype;
        defineProperty(Map, symbolSpecies, function (obj) {
          var constructor = this;
          var prototype = constructor.prototype || Map$prototype;
          var object = obj || create(prototype);
          defineProperties(object, { _es6map: true });
          return object;
        });

        Value.getter(Map.prototype, 'size', function () {
          if (typeof this._size === 'undefined') {
            throw new TypeError('size method called on incompatible Map');
          }
          return this._size;
        });

        defineProperties(Map.prototype, {
          get: function (key) {
            var fkey = fastkey(key);
            if (fkey !== null) {
              // fast O(1) path
              var entry = this._storage[fkey];
              if (entry) {
                return entry.value;
              } else {
                return;
              }
            }
            var head = this._head, i = head;
            while ((i = i.next) !== head) {
              if (ES.SameValueZero(i.key, key)) {
                return i.value;
              }
            }
          },

          has: function (key) {
            var fkey = fastkey(key);
            if (fkey !== null) {
              // fast O(1) path
              return typeof this._storage[fkey] !== 'undefined';
            }
            var head = this._head, i = head;
            while ((i = i.next) !== head) {
              if (ES.SameValueZero(i.key, key)) {
                return true;
              }
            }
            return false;
          },

          set: function (key, value) {
            var head = this._head, i = head, entry;
            var fkey = fastkey(key);
            if (fkey !== null) {
              // fast O(1) path
              if (typeof this._storage[fkey] !== 'undefined') {
                this._storage[fkey].value = value;
                return this;
              } else {
                entry = this._storage[fkey] = new MapEntry(key, value);
                i = head.prev;
                // fall through
              }
            }
            while ((i = i.next) !== head) {
              if (ES.SameValueZero(i.key, key)) {
                i.value = value;
                return this;
              }
            }
            entry = entry || new MapEntry(key, value);
            if (ES.SameValue(-0, key)) {
              entry.key = +0; // coerce -0 to +0 in entry
            }
            entry.next = this._head;
            entry.prev = this._head.prev;
            entry.prev.next = entry;
            entry.next.prev = entry;
            this._size += 1;
            return this;
          },

          'delete': function (key) {
            var head = this._head, i = head;
            var fkey = fastkey(key);
            if (fkey !== null) {
              // fast O(1) path
              if (typeof this._storage[fkey] === 'undefined') {
                return false;
              }
              i = this._storage[fkey].prev;
              delete this._storage[fkey];
              // fall through
            }
            while ((i = i.next) !== head) {
              if (ES.SameValueZero(i.key, key)) {
                i.key = i.value = empty;
                i.prev.next = i.next;
                i.next.prev = i.prev;
                this._size -= 1;
                return true;
              }
            }
            return false;
          },

          clear: function clear() {
            this._size = 0;
            this._storage = emptyObject();
            var head = this._head, i = head, p = i.next;
            while ((i = p) !== head) {
              i.key = i.value = empty;
              p = i.next;
              i.next = i.prev = head;
            }
            head.next = head.prev = head;
          },

          keys: function keys() {
            return new MapIterator(this, 'key');
          },

          values: function values() {
            return new MapIterator(this, 'value');
          },

          entries: function entries() {
            return new MapIterator(this, 'key+value');
          },

          forEach: function forEach(callback) {
            var context = arguments.length > 1 ? arguments[1] : null;
            var it = this.entries();
            for (var entry = it.next(); !entry.done; entry = it.next()) {
              if (context) {
                callback.call(context, entry.value[1], entry.value[0], this);
              } else {
                callback(entry.value[1], entry.value[0], this);
              }
            }
          }
        });
        addIterator(Map.prototype, function () { return this.entries(); });

        return Map;
      }()),

      Set: (function () {
        // Creating a Map is expensive.  To speed up the common case of
        // Sets containing only string or numeric keys, we use an object
        // as backing storage and lazily create a full Map only when
        // required.
        var SetShim = function Set() {
          var set = this;
          if (!ES.TypeIsObject(set)) {
            throw new TypeError("Constructor Set requires 'new'");
          }
          set = emulateES6construct(set);
          if (!set._es6set) {
            throw new TypeError('bad set');
          }

          defineProperties(set, {
            '[[SetData]]': null,
            _storage: emptyObject()
          });

          // Optionally initialize map from iterable
          if (arguments.length > 0 && typeof arguments[0] !== 'undefined' && arguments[0] !== null) {
            var it = ES.GetIterator(arguments[0]);
            var adder = set.add;
            if (!ES.IsCallable(adder)) { throw new TypeError('bad set'); }
            while (true) {
              var next = ES.IteratorNext(it);
              if (next.done) { break; }
              var nextItem = next.value;
              adder.call(set, nextItem);
            }
          }
          return set;
        };
        var Set$prototype = SetShim.prototype;
        defineProperty(SetShim, symbolSpecies, function (obj) {
          var constructor = this;
          var prototype = constructor.prototype || Set$prototype;
          var object = obj || create(prototype);
          defineProperties(object, { _es6set: true });
          return object;
        });

        // Switch from the object backing storage to a full Map.
        var ensureMap = function ensureMap(set) {
          if (!set['[[SetData]]']) {
            var m = set['[[SetData]]'] = new collectionShims.Map();
            Object.keys(set._storage).forEach(function (k) {
              // fast check for leading '$'
              if (k.charCodeAt(0) === 36) {
                k = k.slice(1);
              } else if (k.charAt(0) === 'n') {
                k = +k.slice(1);
              } else {
                k = +k;
              }
              m.set(k, k);
            });
            set._storage = null; // free old backing storage
          }
        };

        Value.getter(SetShim.prototype, 'size', function () {
          if (typeof this._storage === 'undefined') {
            // https://github.com/paulmillr/es6-shim/issues/176
            throw new TypeError('size method called on incompatible Set');
          }
          ensureMap(this);
          return this['[[SetData]]'].size;
        });

        defineProperties(SetShim.prototype, {
          has: function (key) {
            var fkey;
            if (this._storage && (fkey = fastkey(key)) !== null) {
              return !!this._storage[fkey];
            }
            ensureMap(this);
            return this['[[SetData]]'].has(key);
          },

          add: function (key) {
            var fkey;
            if (this._storage && (fkey = fastkey(key)) !== null) {
              this._storage[fkey] = true;
              return this;
            }
            ensureMap(this);
            this['[[SetData]]'].set(key, key);
            return this;
          },

          'delete': function (key) {
            var fkey;
            if (this._storage && (fkey = fastkey(key)) !== null) {
              var hasFKey = _hasOwnProperty(this._storage, fkey);
              return (delete this._storage[fkey]) && hasFKey;
            }
            ensureMap(this);
            return this['[[SetData]]']['delete'](key);
          },

          clear: function clear() {
            if (this._storage) {
              this._storage = emptyObject();
            } else {
              this['[[SetData]]'].clear();
            }
          },

          values: function values() {
            ensureMap(this);
            return this['[[SetData]]'].values();
          },

          entries: function entries() {
            ensureMap(this);
            return this['[[SetData]]'].entries();
          },

          forEach: function forEach(callback) {
            var context = arguments.length > 1 ? arguments[1] : null;
            var entireSet = this;
            ensureMap(entireSet);
            this['[[SetData]]'].forEach(function (value, key) {
              if (context) {
                callback.call(context, key, key, entireSet);
              } else {
                callback(key, key, entireSet);
              }
            });
          }
        });
        defineProperty(SetShim, 'keys', SetShim.values, true);
        addIterator(SetShim.prototype, function () { return this.values(); });

        return SetShim;
      }())
    };
    defineProperties(globals, collectionShims);

    if (globals.Map || globals.Set) {
      // Safari 8, for example, doesn't accept an iterable.
      var mapAcceptsArguments = valueOrFalseIfThrows(function () { return new Map([[1, 2]]).get(1) === 2; });
      if (!mapAcceptsArguments) {
        var OrigMapNoArgs = globals.Map;
        globals.Map = function Map() {
          if (!(this instanceof Map)) {
            throw new TypeError('Constructor Map requires "new"');
          }
          var m = new OrigMapNoArgs();
          var iterable;
          if (arguments.length > 0) {
            iterable = arguments[0];
          }
          if (Array.isArray(iterable) || Type.string(iterable)) {
            Array.prototype.forEach.call(iterable, function (entry) {
              m.set(entry[0], entry[1]);
            });
          } else if (iterable instanceof Map) {
            Map.prototype.forEach.call(iterable, function (value, key) {
              m.set(key, value);
            });
          }
          Object.setPrototypeOf(m, globals.Map.prototype);
          defineProperty(m, 'constructor', Map, true);
          return m;
        };
        globals.Map.prototype = create(OrigMapNoArgs.prototype);
        Value.preserveToString(globals.Map, OrigMapNoArgs);
      }
      var m = new Map();
      var mapUsesSameValueZero = (function (m) {
        m['delete'](0);
        m['delete'](-0);
        m.set(0, 3);
        m.get(-0, 4);
        return m.get(0) === 3 && m.get(-0) === 4;
      }(m));
      var mapSupportsChaining = m.set(1, 2) === m;
      if (!mapUsesSameValueZero || !mapSupportsChaining) {
        var origMapSet = Map.prototype.set;
        overrideNative(Map.prototype, 'set', function set(k, v) {
          origMapSet.call(this, k === 0 ? 0 : k, v);
          return this;
        });
      }
      if (!mapUsesSameValueZero) {
        var origMapGet = Map.prototype.get;
        var origMapHas = Map.prototype.has;
        defineProperties(Map.prototype, {
          get: function get(k) {
            return origMapGet.call(this, k === 0 ? 0 : k);
          },
          has: function has(k) {
            return origMapHas.call(this, k === 0 ? 0 : k);
          }
        }, true);
        Value.preserveToString(Map.prototype.get, origMapGet);
        Value.preserveToString(Map.prototype.has, origMapHas);
      }
      var s = new Set();
      var setUsesSameValueZero = (function (s) {
        s['delete'](0);
        s.add(-0);
        return !s.has(0);
      }(s));
      var setSupportsChaining = s.add(1) === s;
      if (!setUsesSameValueZero || !setSupportsChaining) {
        var origSetAdd = Set.prototype.add;
        Set.prototype.add = function add(v) {
          origSetAdd.call(this, v === 0 ? 0 : v);
          return this;
        };
        Value.preserveToString(Set.prototype.add, origSetAdd);
      }
      if (!setUsesSameValueZero) {
        var origSetHas = Set.prototype.has;
        Set.prototype.has = function has(v) {
          return origSetHas.call(this, v === 0 ? 0 : v);
        };
        Value.preserveToString(Set.prototype.has, origSetHas);
        var origSetDel = Set.prototype['delete'];
        Set.prototype['delete'] = function SetDelete(v) {
          return origSetDel.call(this, v === 0 ? 0 : v);
        };
        Value.preserveToString(Set.prototype['delete'], origSetDel);
      }
      var mapSupportsSubclassing = supportsSubclassing(globals.Map, function (M) {
        var m = new M([]);
        // Firefox 32 is ok with the instantiating the subclass but will
        // throw when the map is used.
        m.set(42, 42);
        return m instanceof M;
      });
      var mapFailsToSupportSubclassing = Object.setPrototypeOf && !mapSupportsSubclassing; // without Object.setPrototypeOf, subclassing is not possible
      var mapRequiresNew = (function () {
        try {
          return !(globals.Map() instanceof globals.Map);
        } catch (e) {
          return e instanceof TypeError;
        }
      }());
      if (globals.Map.length !== 0 || mapFailsToSupportSubclassing || !mapRequiresNew) {
        var OrigMap = globals.Map;
        globals.Map = function Map() {
          if (!(this instanceof Map)) {
            throw new TypeError('Constructor Map requires "new"');
          }
          var m = arguments.length > 0 ? new OrigMap(arguments[0]) : new OrigMap();
          Object.setPrototypeOf(m, Map.prototype);
          defineProperty(m, 'constructor', Map, true);
          return m;
        };
        globals.Map.prototype = create(OrigMap.prototype);
        Value.preserveToString(globals.Map, OrigMap);
      }
      var setSupportsSubclassing = supportsSubclassing(globals.Set, function (S) {
        var s = new S([]);
        s.add(42, 42);
        return s instanceof S;
      });
      var setFailsToSupportSubclassing = Object.setPrototypeOf && !setSupportsSubclassing; // without Object.setPrototypeOf, subclassing is not possible
      var setRequiresNew = (function () {
        try {
          return !(globals.Set() instanceof globals.Set);
        } catch (e) {
          return e instanceof TypeError;
        }
      }());
      if (globals.Set.length !== 0 || setFailsToSupportSubclassing || !setRequiresNew) {
        var OrigSet = globals.Set;
        globals.Set = function Set() {
          if (!(this instanceof Set)) {
            throw new TypeError('Constructor Set requires "new"');
          }
          var s = arguments.length > 0 ? new OrigSet(arguments[0]) : new OrigSet();
          Object.setPrototypeOf(s, Set.prototype);
          defineProperty(s, 'constructor', Set, true);
          return s;
        };
        globals.Set.prototype = create(OrigSet.prototype);
        Value.preserveToString(globals.Set, OrigSet);
      }
      var mapIterationThrowsStopIterator = !valueOrFalseIfThrows(function () {
        return (new Map()).keys().next().done;
      });
      /*
        - In Firefox < 23, Map#size is a function.
        - In all current Firefox, Set#entries/keys/values & Map#clear do not exist
        - https://bugzilla.mozilla.org/show_bug.cgi?id=869996
        - In Firefox 24, Map and Set do not implement forEach
        - In Firefox 25 at least, Map and Set are callable without "new"
      */
      if (
        typeof globals.Map.prototype.clear !== 'function' ||
        new globals.Set().size !== 0 ||
        new globals.Map().size !== 0 ||
        typeof globals.Map.prototype.keys !== 'function' ||
        typeof globals.Set.prototype.keys !== 'function' ||
        typeof globals.Map.prototype.forEach !== 'function' ||
        typeof globals.Set.prototype.forEach !== 'function' ||
        isCallableWithoutNew(globals.Map) ||
        isCallableWithoutNew(globals.Set) ||
        typeof (new globals.Map().keys().next) !== 'function' || // Safari 8
        mapIterationThrowsStopIterator || // Firefox 25
        !mapSupportsSubclassing
      ) {
        delete globals.Map; // necessary to overwrite in Safari 8
        delete globals.Set; // necessary to overwrite in Safari 8
        defineProperties(globals, {
          Map: collectionShims.Map,
          Set: collectionShims.Set
        }, true);
      }
    }
    if (globals.Set.prototype.keys !== globals.Set.prototype.values) {
      defineProperty(globals.Set.prototype, 'keys', globals.Set.prototype.values, true);
    }
    // Shim incomplete iterator implementations.
    addIterator(Object.getPrototypeOf((new globals.Map()).keys()));
    addIterator(Object.getPrototypeOf((new globals.Set()).keys()));
  }

  // Reflect
  if (!globals.Reflect) {
    defineProperty(globals, 'Reflect', {});
  }
  var Reflect = globals.Reflect;

  var throwUnlessTargetIsObject = function throwUnlessTargetIsObject(target) {
    if (!ES.TypeIsObject(target)) {
      throw new TypeError('target must be an object');
    }
  };

  // Some Reflect methods are basically the same as
  // those on the Object global, except that a TypeError is thrown if
  // target isn't an object. As well as returning a boolean indicating
  // the success of the operation.
  defineProperties(globals.Reflect, {
    // Apply method in a functional form.
    apply: function apply() {
      return ES.Call.apply(null, arguments);
    },

    // New operator in a functional form.
    construct: function construct(constructor, args) {
      if (!ES.IsCallable(constructor)) {
        throw new TypeError('First argument must be callable.');
      }

      return ES.Construct(constructor, args);
    },

    // When deleting a non-existent or configurable property,
    // true is returned.
    // When attempting to delete a non-configurable property,
    // it will return false.
    deleteProperty: function deleteProperty(target, key) {
      throwUnlessTargetIsObject(target);
      if (supportsDescriptors) {
        var desc = Object.getOwnPropertyDescriptor(target, key);

        if (desc && !desc.configurable) {
          return false;
        }
      }

      // Will return true.
      return delete target[key];
    },

    enumerate: function enumerate(target) {
      throwUnlessTargetIsObject(target);
      return new ObjectIterator(target, 'key');
    },

    has: function has(target, key) {
      throwUnlessTargetIsObject(target);
      return key in target;
    }
  });

  if (Object.getOwnPropertyNames) {
    defineProperties(globals.Reflect, {
      // Basically the result of calling the internal [[OwnPropertyKeys]].
      // Concatenating propertyNames and propertySymbols should do the trick.
      // This should continue to work together with a Symbol shim
      // which overrides Object.getOwnPropertyNames and implements
      // Object.getOwnPropertySymbols.
      ownKeys: function ownKeys(target) {
        throwUnlessTargetIsObject(target);
        var keys = Object.getOwnPropertyNames(target);

        if (ES.IsCallable(Object.getOwnPropertySymbols)) {
          keys.push.apply(keys, Object.getOwnPropertySymbols(target));
        }

        return keys;
      }
    });
  }

  var callAndCatchException = function ConvertExceptionToBoolean(func) {
    return !throwsError(func);
  };

  if (Object.preventExtensions) {
    defineProperties(globals.Reflect, {
      isExtensible: function isExtensible(target) {
        throwUnlessTargetIsObject(target);
        return Object.isExtensible(target);
      },
      preventExtensions: function preventExtensions(target) {
        throwUnlessTargetIsObject(target);
        return callAndCatchException(function () {
          Object.preventExtensions(target);
        });
      }
    });
  }

  if (supportsDescriptors) {
    var internalGet = function get(target, key, receiver) {
      var desc = Object.getOwnPropertyDescriptor(target, key);

      if (!desc) {
        var parent = Object.getPrototypeOf(target);

        if (parent === null) {
          return undefined;
        }

        return internalGet(parent, key, receiver);
      }

      if ('value' in desc) {
        return desc.value;
      }

      if (desc.get) {
        return desc.get.call(receiver);
      }

      return undefined;
    };

    var internalSet = function set(target, key, value, receiver) {
      var desc = Object.getOwnPropertyDescriptor(target, key);

      if (!desc) {
        var parent = Object.getPrototypeOf(target);

        if (parent !== null) {
          return internalSet(parent, key, value, receiver);
        }

        desc = {
          value: void 0,
          writable: true,
          enumerable: true,
          configurable: true
        };
      }

      if ('value' in desc) {
        if (!desc.writable) {
          return false;
        }

        if (!ES.TypeIsObject(receiver)) {
          return false;
        }

        var existingDesc = Object.getOwnPropertyDescriptor(receiver, key);

        if (existingDesc) {
          return Reflect.defineProperty(receiver, key, {
            value: value
          });
        } else {
          return Reflect.defineProperty(receiver, key, {
            value: value,
            writable: true,
            enumerable: true,
            configurable: true
          });
        }
      }

      if (desc.set) {
        desc.set.call(receiver, value);
        return true;
      }

      return false;
    };

    defineProperties(globals.Reflect, {
      defineProperty: function defineProperty(target, propertyKey, attributes) {
        throwUnlessTargetIsObject(target);
        return callAndCatchException(function () {
          Object.defineProperty(target, propertyKey, attributes);
        });
      },

      getOwnPropertyDescriptor: function getOwnPropertyDescriptor(target, propertyKey) {
        throwUnlessTargetIsObject(target);
        return Object.getOwnPropertyDescriptor(target, propertyKey);
      },

      // Syntax in a functional form.
      get: function get(target, key) {
        throwUnlessTargetIsObject(target);
        var receiver = arguments.length > 2 ? arguments[2] : target;

        return internalGet(target, key, receiver);
      },

      set: function set(target, key, value) {
        throwUnlessTargetIsObject(target);
        var receiver = arguments.length > 3 ? arguments[3] : target;

        return internalSet(target, key, value, receiver);
      }
    });
  }

  if (Object.getPrototypeOf) {
    var objectDotGetPrototypeOf = Object.getPrototypeOf;
    defineProperties(globals.Reflect, {
      getPrototypeOf: function getPrototypeOf(target) {
        throwUnlessTargetIsObject(target);
        return objectDotGetPrototypeOf(target);
      }
    });
  }

  if (Object.setPrototypeOf) {
    var willCreateCircularPrototype = function (object, proto) {
      while (proto) {
        if (object === proto) {
          return true;
        }
        proto = Reflect.getPrototypeOf(proto);
      }
      return false;
    };

    defineProperties(globals.Reflect, {
      // Sets the prototype of the given object.
      // Returns true on success, otherwise false.
      setPrototypeOf: function setPrototypeOf(object, proto) {
        throwUnlessTargetIsObject(object);
        if (proto !== null && !ES.TypeIsObject(proto)) {
          throw new TypeError('proto must be an object or null');
        }

        // If they already are the same, we're done.
        if (proto === Reflect.getPrototypeOf(object)) {
          return true;
        }

        // Cannot alter prototype if object not extensible.
        if (Reflect.isExtensible && !Reflect.isExtensible(object)) {
          return false;
        }

        // Ensure that we do not create a circular prototype chain.
        if (willCreateCircularPrototype(object, proto)) {
          return false;
        }

        Object.setPrototypeOf(object, proto);

        return true;
      }
    });
  }

  if (String(new Date(NaN)) !== 'Invalid Date') {
    var dateToString = Date.prototype.toString;
    var shimmedDateToString = function toString() {
      var valueOf = +this;
      if (valueOf !== valueOf) {
        return 'Invalid Date';
      }
      return dateToString.call(this);
    };
    overrideNative(Date.prototype, 'toString', shimmedDateToString);
  }

  // Annex B HTML methods
  // https://people.mozilla.org/~jorendorff/es6-draft.html#sec-additional-properties-of-the-string.prototype-object
  var stringHTMLshims = {
    anchor: function anchor(name) { return ES.CreateHTML(this, 'a', 'name', name); },
    big: function big() { return ES.CreateHTML(this, 'big', '', ''); },
    blink: function blink() { return ES.CreateHTML(this, 'blink', '', ''); },
    bold: function bold() { return ES.CreateHTML(this, 'b', '', ''); },
    fixed: function fixed() { return ES.CreateHTML(this, 'tt', '', ''); },
    fontcolor: function fontcolor(color) { return ES.CreateHTML(this, 'font', 'color', color); },
    fontsize: function fontsize(size) { return ES.CreateHTML(this, 'font', 'size', size); },
    italics: function italics() { return ES.CreateHTML(this, 'i', '', ''); },
    link: function link(url) { return ES.CreateHTML(this, 'a', 'href', url); },
    small: function small() { return ES.CreateHTML(this, 'small', '', ''); },
    strike: function strike() { return ES.CreateHTML(this, 'strike', '', ''); },
    sub: function sub() { return ES.CreateHTML(this, 'sub', '', ''); },
    sup: function sub() { return ES.CreateHTML(this, 'sup', '', ''); }
  };
  defineProperties(String.prototype, stringHTMLshims);
  Object.keys(stringHTMLshims).forEach(function (key) {
    var method = String.prototype[key];
    var shouldOverwrite = false;
    if (ES.IsCallable(method)) {
      var output = method.call('', ' " ');
      var quotesCount = [].concat(output.match(/"/g)).length;
      shouldOverwrite = output !== output.toLowerCase() || quotesCount > 2;
    } else {
      shouldOverwrite = true;
    }
    if (shouldOverwrite) {
      defineProperty(String.prototype, key, stringHTMLshims[key], true);
    }
  });

  return globals;
}));