[ident-function-substitution.html]
  [var() in the ident() argument]
    expected: FAIL

  [attr() in the ident() argument]
    expected: FAIL

  [ident() in the ident() argument]
    expected: FAIL

  [ident() building the var() name argument from an attribute]
    expected: FAIL

  [sibling-index() in the ident() argument]
    expected: FAIL

  [a math function over sibling-index() in the ident() argument]
    expected: FAIL

  [an argument that is not <ident-arg>+ makes ident() invalid at computed-value time]
    expected: FAIL

  [an ident() with no attr() involved does not taint the property it names]
    expected: FAIL

  [ident() substituting a value the property does not accept]
    expected: FAIL