Nullptr crash under RenderTreeBuilder::Inline::splitInlines while transitioning to fullscreen

[anttijk]

30fb035

Nullptr crash under RenderTreeBuilder::Inline::splitInlines while transitioning to fullscreen
https://bugs.webkit.org/show_bug.cgi?id=282231
rdar://137177522

Reviewed by Alan Baradlay.

* LayoutTests/fast/css/fullscreen-style-sharing-crash-expected.txt: Added.
* LayoutTests/fast/css/fullscreen-style-sharing-crash.html: Added.
* Source/WebCore/style/StyleSharingResolver.cpp:
(WebCore::Style::SharingResolver::canShareStyleWithElement const):

We were improperly sharing style between elements that had different top layer status and fullscreen flags.
This led to illegal render tree structure.

Canonical link: https://commits.webkit.org/285832@main

67fa0f9

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	❌ 🧪 wpe-wk2	✅ 🧪 win-tests
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	❌ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-cairo
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	❌ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	✅ 🧪 api-gtk
✅ 🛠 🧪 merge	⏳ 🧪 vision-wk2	✅ 🧪 mac-intel-wk2
	✅ 🛠 tv	❌ 🛠 mac-safer-cpp
	✅ 🛠 tv-sim
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash ea18c9a)

Details

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	⏳ 🧪 wpe-wk2	❌ 🧪 win-tests
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-cairo
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	🧪 gtk-wk2
	✅ 🛠 vision-sim	❌ 🧪 mac-wk2-stress	⏳ 🧪 api-gtk
	✅ 🧪 vision-wk2	⏳ 🧪 mac-intel-wk2
	✅ 🛠 tv	🛠 mac-safer-cpp
	✅ 🛠 tv-sim
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash 25c05e0)

Details

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	🛠 wpe	✅ 🛠 win
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	🧪 wpe-wk2	🧪 win-tests
✅ 🧪 webkitperl	🧪 ios-wk2	🧪 api-mac	🧪 api-wpe
	🧪 ios-wk2-wpt	🧪 mac-wk1	✅ 🛠 wpe-cairo
	🧪 api-ios	🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 vision	🧪 mac-AS-debug-wk2	🧪 gtk-wk2
	✅ 🛠 vision-sim	🧪 mac-wk2-stress	⏳ 🧪 api-gtk
	🧪 vision-wk2	⏳ 🧪 mac-intel-wk2
	✅ 🛠 tv	🛠 mac-safer-cpp
	✅ 🛠 tv-sim
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on current version of this PR (hash 67fa0f9)

Details

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	❌ 🧪 wpe-wk2	✅ 🧪 win-tests
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	❌ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-cairo
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	❌ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	✅ 🧪 api-gtk
✅ 🛠 🧪 merge	⏳ 🧪 vision-wk2	✅ 🧪 mac-intel-wk2
	✅ 🛠 tv	❌ 🛠 mac-safer-cpp
	✅ 🛠 tv-sim
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-commit-queue]

Committed 285832@main (30fb035): https://commits.webkit.org/285832@main

Reviewed commits have been landed. Closing PR #35857 and removing active labels.