MutationObserver.observe() incorrectly throws when attributeOldValue or characterDataOldValue is present with value false

[cdumez]

a811f8d

MutationObserver.observe() incorrectly throws when attributeOldValue or characterDataOldValue is present with value false
https://bugs.webkit.org/show_bug.cgi?id=316382

Reviewed by Ryosuke Niwa.

Per https://dom.spec.whatwg.org/#dom-mutationobserver-observe, if either
attributeOldValue or attributeFilter is *present* in the init dictionary
and attributes is omitted, attributes is set to true. The same applies to
characterDataOldValue and characterData. "Present" here means the
dictionary key was provided, regardless of its value.

WebKit was conflating presence with truthiness: AttributeOldValue /
CharacterDataOldValue option flags were only added when the value was
true, and the auto-set step keyed off those flags rather than off
presence. As a result, observe(node, { attributeOldValue: false }) — and
likewise for characterDataOldValue: false — incorrectly threw a
TypeError instead of registering an attribute observer with no
old-value delivery.

Use std::optional::has_value() to test presence in the auto-set step,
matching Blink & Gecko's behavior and the spec.

Test: imported/w3c/web-platform-tests/dom/nodes/MutationObserver-sanity.html

* LayoutTests/imported/w3c/web-platform-tests/dom/nodes/MutationObserver-sanity-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/dom/nodes/MutationObserver-sanity.html:
* Source/WebCore/dom/MutationObserver.cpp:
(WebCore::MutationObserver::observe):

Canonical link: https://commits.webkit.org/314623@main

787d63f

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win	✅ 🛠 ios-apple
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	🧪 win-tests	✅ 🛠 mac-apple
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe		✅ 🛠 vision-apple
	✅ 🧪 ios-wk2-wpt	✅ 🧪 api-mac-debug	✅ 🛠 gtk3-libwebrtc
	🧪 api-ios	✅ 🧪 mac-wk1	✅ 🛠 gtk
	✅ 🛠 ios-safer-cpp	✅ 🧪 mac-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	✅ 🛠 playstation
	✅ 🧪 vision-wk2	✅ 🧪 mac-intel-wk2
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp
	✅ 🛠 tv-sim	❌ 🧪 mac-site-isolation
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on current version of this PR (hash 787d63f)

Details

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win	✅ 🛠 ios-apple
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	🧪 win-tests	✅ 🛠 mac-apple
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe		✅ 🛠 vision-apple
	✅ 🧪 ios-wk2-wpt	✅ 🧪 api-mac-debug	✅ 🛠 gtk3-libwebrtc
	🧪 api-ios	✅ 🧪 mac-wk1	✅ 🛠 gtk
	✅ 🛠 ios-safer-cpp	✅ 🧪 mac-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	✅ 🛠 playstation
	✅ 🧪 vision-wk2	✅ 🧪 mac-intel-wk2
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp
	✅ 🛠 tv-sim	❌ 🧪 mac-site-isolation
	✅ 🛠 watch
	✅ 🛠 watch-sim

[cdumez]

Test upstreaming: web-platform-tests/wpt#60421

[webkit-commit-queue]

Committed 314623@main (a811f8d): https://commits.webkit.org/314623@main

Reviewed commits have been landed. Closing PR #66529 and removing active labels.