Pass and use better parent/root information to (re)moving steps.

[dbaron]

For removing steps and moving steps, instead of passing only oldParent (which is null when the removed node is not the root of the removed subtree), pass both oldAncestor (never null) and isSubtreeRoot.

This updates element removing steps as needed, fixing spec bugs (apparently not reflected as implementation bugs) for a/area and for selectedcontent.

This is the HTML spec part of the fix for #12098
For the DOM spec change see whatwg/dom#1450

• At least two implementers are interested (and none opposed):
  • Chromium
  • Gecko (assuming use of oldParent in HTML element removing steps is sometimes wrong #12098 (comment) is sufficient)
• Tests are written and can be reviewed and commented upon at:
  • I think this probably doesn't need tests since previous implementors and test authors assumed that the spec said what this pair of PRs is updating it to actually say.
• Implementation bugs are filed:
  • N/A
• 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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/embedded-content.html ( diff )
/form-elements.html ( diff )
/infrastructure.html ( diff )
/interactive-elements.html ( diff )
/links.html ( diff )

[dbaron]

Also note that this also fixes a minor error in the general definition of "HTML element moving steps", where it wasn't passing oldParent through from the DOM spec's "moving steps" through to the individual HTML element definitions.

[annevk]

Looks good modulo nits.