[JSC] Use synchronous GCActivityCallback GC with RunLoopObserver

[Constellation]

e0c479c

[JSC] Use synchronous GCActivityCallback GC with RunLoopObserver
https://bugs.webkit.org/show_bug.cgi?id=265515
rdar://118930139

Reviewed by Wenson Hsieh.

Now we can schedule GC only when we are idle from GCActivityCallback. So we do not need to run async version.
This patch changes two things.

1. We set up RunLoopObserver and run GC when RunLoop gets idle state after GCActivityCallback detects GC opportunities.
2. We use sync GC instead of async GC since we now run this only when we are idle. We do not need to run async version.

* Source/JavaScriptCore/heap/EdenGCActivityCallback.cpp:
(JSC::EdenGCActivityCallback::EdenGCActivityCallback):
(JSC::EdenGCActivityCallback::doCollection):
* Source/JavaScriptCore/heap/EdenGCActivityCallback.h:
(JSC::EdenGCActivityCallback::tryCreate):
* Source/JavaScriptCore/heap/FullGCActivityCallback.cpp:
(JSC::FullGCActivityCallback::FullGCActivityCallback):
(JSC::FullGCActivityCallback::doCollection):
* Source/JavaScriptCore/heap/FullGCActivityCallback.h:
(JSC::FullGCActivityCallback::tryCreate):
* Source/JavaScriptCore/heap/GCActivityCallback.cpp:
(JSC::GCActivityCallback::GCActivityCallback):
* Source/JavaScriptCore/heap/GCActivityCallback.h:
* Source/JavaScriptCore/heap/Synchronousness.h:
* Source/WebCore/page/OpportunisticTaskScheduler.cpp:
(WebCore::OpportunisticTaskScheduler::FullGCActivityCallback::FullGCActivityCallback):
(WebCore::OpportunisticTaskScheduler::FullGCActivityCallback::doCollection):
(WebCore::OpportunisticTaskScheduler::EdenGCActivityCallback::EdenGCActivityCallback):
(WebCore::OpportunisticTaskScheduler::EdenGCActivityCallback::doCollection):
* Source/WebCore/page/OpportunisticTaskScheduler.h:

Canonical link: https://commits.webkit.org/271324@main

5e9f357

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 gtk
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🧪 gtk-wk2
✅ 🛠 🧪 jsc-arm64	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 api-gtk
	✅ 🛠 tv-sim		✅ 🛠 jsc-armv7
	✅ 🛠 watch		❌ 🧪 jsc-armv7-tests
✅ 🛠 🧪 unsafe-merge	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash 49f77af)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	❌ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 gtk
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🧪 gtk-wk2
✅ 🛠 🧪 jsc-arm64	✅ 🛠 tv	❌ 🧪 mac-AS-debug-wk2	✅ 🧪 api-gtk
	✅ 🛠 tv-sim		✅ 🛠 jsc-armv7
	✅ 🛠 watch		❌ 🧪 jsc-armv7-tests
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on current version of this PR (hash 5e9f357)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 gtk
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🧪 gtk-wk2
✅ 🛠 🧪 jsc-arm64	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 api-gtk
	✅ 🛠 tv-sim		✅ 🛠 jsc-armv7
	✅ 🛠 watch		❌ 🧪 jsc-armv7-tests
✅ 🛠 🧪 unsafe-merge	✅ 🛠 watch-sim

[webkit-commit-queue]

Committed 271324@main (e0c479c): https://commits.webkit.org/271324@main

Reviewed commits have been landed. Closing PR #21050 and removing active labels.