[GTK][WPE] Fix an assert when threaded compositor is invalidated right before renderLayerTree is called

[carlosgcampos]

42c5ccc

[GTK][WPE] Fix an assert when threaded compositor is invalidated right before renderLayerTree is called
https://bugs.webkit.org/show_bug.cgi?id=304395

Reviewed by Nikolas Zimmermann.

The main thread invalidates the threaded compositor, which switches to
Idle state, right before renderLayerTree is called in the compositing
thread that hits the assert checking state should be Scheduled. We
should return early from renderLayerTree if the timer has already been
stopped.

Canonical link: https://commits.webkit.org/304667@main

c74d426

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

[webkit-early-warning-system]

EWS run on current version of this PR (hash c74d426)

Details

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

[webkit-commit-queue]

Committed 304667@main (42c5ccc): https://commits.webkit.org/304667@main

Reviewed commits have been landed. Closing PR #55617 and removing active labels.