GraphicsContextGL::m_layerComposited is a redundant flag

[kkinnunen-apple]

db15813

GraphicsContextGL::m_layerComposited is a redundant flag
https://bugs.webkit.org/show_bug.cgi?id=263772
rdar://117582088

Reviewed by Don Olmstead.

The flag would be queried by
WebGLRenderingContextBase::clearIfComposited to understand if the
backbuffer needs to be cleared after prepareForDisplay before next draw
call. This is already taken care of by buffersToAutoClear variable which
tracks this state and is reset in same location, at prepareForDisplay.

The flag would be queried by GraphicsContextGL prepareForDisplay
implementations. This is taken care of by the caller, e.g. the caller
only schedules a prepare when draw has happened.

Work towards simplifying the default framebuffer implementation, in
order to implement premultipliedAlpha compositing.

* Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp:
(WebCore::WebGLRenderingContextBase::clearIfComposited):
(WebCore::WebGLRenderingContextBase::prepareForDisplay):
* Source/WebCore/platform/graphics/GraphicsContextGL.cpp:
(WebCore::GraphicsContextGL::markContextChanged):
(WebCore::GraphicsContextGL::markLayerComposited):
(WebCore::GraphicsContextGL::layerComposited const): Deleted.
* Source/WebCore/platform/graphics/GraphicsContextGL.h:
* Source/WebCore/platform/graphics/cocoa/GraphicsContextGLCocoa.mm:
(WebCore::GraphicsContextGLCocoa::prepareForDisplayWithFinishedSignal):
* Source/WebCore/platform/graphics/gbm/GraphicsContextGLGBM.cpp:
(WebCore::GraphicsContextGLGBM::prepareForDisplay):
* Source/WebCore/platform/graphics/texmap/GraphicsContextGLTextureMapperANGLE.cpp:
(WebCore::GraphicsContextGLTextureMapperANGLE::prepareForDisplay):
* Source/WebKit/WebProcess/GPU/graphics/RemoteGraphicsContextGLProxy.cpp:
(WebKit::RemoteGraphicsContextGLProxy::markContextChanged):

Canonical link: https://commits.webkit.org/269939@main

6c201cc

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
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✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	🧪 wpe-wk2
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	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🧪 gtk-wk2
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	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2
	✅ 🛠 tv-sim
✅ 🛠 🧪 merge	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash 93e33e0)

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	✅ 🛠 gtk
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🧪 gtk-wk2
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🧪 api-gtk
	✅ 🛠 tv	❌ 🧪 mac-AS-debug-wk2
	✅ 🛠 tv-sim
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on current version of this PR (hash 6c201cc)

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	✅ 🛠 gtk
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🧪 gtk-wk2
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🧪 api-gtk
	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2
	✅ 🛠 tv-sim
✅ 🛠 🧪 merge	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-commit-queue]

Committed 269939@main (db15813): https://commits.webkit.org/269939@main

Reviewed commits have been landed. Closing PR #19633 and removing active labels.