Implement support for <dialog> element cancel event

[Tim Nguyen (:ntim)]

Pressing "Esc" should "cancel" the dialog: e.g. close it, and emit a "cancel" event.

[Tim Nguyen (:ntim)]

This is only for modal dialogs.

[Radar WebKit Bug Importer]

<rdar://problem/79971694>

[Tim Nguyen (:ntim)]

Created attachment 433314 [details]
Patch

[Tim Nguyen (:ntim)]

Created attachment 435004 [details]
Patch

[EWS Watchlist]

This patch modifies the imported WPT tests. Please ensure that any changes on the tests (not coming from a WPT import) are exported to WPT. Please see https://trac.webkit.org/wiki/WPTExportProcess

[Tim Nguyen (:ntim)]

WPT PR: https://github.com/web-platform-tests/wpt/pull/29917

[Chris Dumez]

Comment on attachment 435004 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=435004&action=review

r=me

> Source/WebCore/page/EventHandler.cpp:3514
> +    if (HTMLDialogElement* activeModalDialog = m_frame.document()->activeModalDialog()) {

auto*

[Tim Nguyen (:ntim)]

Created attachment 435021 [details]
Patch

[Tim Nguyen (:ntim)]

Committed r280703 (240299@main): <https://commits.webkit.org/240299@main>