Do not establish close watchers in non-fully active documents

[domenic]

Closes #10634. See #10659 for a better followup.

• At least two implementers are interested (and none opposed):
  • The previous spec would hit an assert and this is clearly the intent.
• Tests are written and can be reviewed and commented upon at:
  • I don't think we have tests for these cases. We could write them as part of Consider throwing for showModal() and showPopover() in non-fully-active documents #10659 ?
• Implementation bugs are filed:
  • Not necessary as no browser is hitting the assert today
• MDN issue is filed: N/A
• The top of this comment includes a clear commit message to use.

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

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/interactive-elements.html ( diff )
/popover.html ( diff )

[lukewarlow]

The easiest test here would be attach a dialog to the detached document, call .showModal(), use the sendCloseRequest() helper function and assert that the dialog doesn't actually close?

Similarly with popovers?

[keithamus]

The easiest test here would be attach a dialog to the detached document, call .showModal(), use the sendCloseRequest() helper function and assert that the dialog doesn't actually close?

Similarly with popovers?

That'll only hold while #10659 is still open though 😂

[lukewarlow]

Yeah that'll make this change superfluous though so it depends on what the desired outcome is

[domenic]

Yep, that testing strategy sounds right, although it's a bit of a silly test since it's unclear why sending an event (via sendCloseRequest()) to the main document would possibly impact the synthetic ones. And as Keith says the test would need to get changed shortly if we fix #10659. So my instinct would be to merge this without tests, as long as #10659 has some momentum...