Remove fragment parsing special case for input tags

[josepharhar]

A special case was added for fragment parsing <select> when assigning innerHTML of another select element due to a regression bug, which I documented here: #10310 (comment)

However, this special case was copied over to input tags as well, which was recently noticed here but was never implemented in chromium or html5lib-tests: html5lib/html5lib-tests#195

This PR removes this special case to match implementations and tests. Allowing input tags inside select is also something that I'm looking into supporting separately, and this case has been supported in stable chromium for long enough that I don't think it is breaking any websites.

• At least two implementers are interested (and none opposed):
  • Chromium
  • …
• Tests are written and can be reviewed and commented upon at:
  • https://wpt.fyi/results/html/syntax/parsing/html5lib_innerHTML_tests_innerHTML_1.html
• Implementation bugs are filed:
  • Chromium: Already implemented
  • Gecko:
  • WebKit:
• Corresponding HTML AAM & ARIA in HTML issues & PRs: not needed
• MDN issue is filed: not needed
• The top of this comment includes a clear commit message to use.

(See WHATWG Working Mode: Changes for more details.)

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/parsing.html ( diff )

[josepharhar]

After doing more digging, I found the reason why this was added: #10557 (comment)

I just never implmented it. I guess that if we change how input tags are parsed inside select, we could just make the innerHTML case match the regular parsing case.