The html5lib_*.html files in this directory wrap the
tree-construction .dat files in resources/. Each wrapper covers one of
the three input modes: html5lib_url.html (Blob URL),
html5lib_write.html (document.write), and
html5lib_write_single.html (one-character-at-a-time document.write).
Per-test dispatch routes #document-fragment entries through innerHTML
regardless of the wrapper's mode.

The .dat files are maintained directly in resources/. After adding,
removing, or editing one, regenerate the wrappers' variant lists with

  wpt update-built --include html5lib