Ignore unsupported disposal methods when decoding GIF

[Ahmad-S792]

095152b

Ignore unsupported disposal methods when decoding GIF

https://bugs.webkit.org/show_bug.cgi?id=270572

Reviewed by Michael Catanzaro.

Merge: https://chromium.googlesource.com/chromium/blink/+/cdfed72e21acef69547a0266508067d238cd1b06

This fixes potential assertion failure about invalid disposal methods by ignoring
unsupported values when decoding GIF.

The bug is caused by some GIF images containing frames with disposal
method 5. Don't know what the author wanted.

NOTE - Due to lack of 'CPP' tests, I am unable to import test changes.

* Source/WebCore/platform/image-decoders/gif/GIFImageReader.cpp:
(GIFImageReader::parse):

Canonical link: https://commits.webkit.org/275749@main

1cbc600

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

[webkit-early-warning-system]

EWS run on current version of this PR (hash 1cbc600)

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	✅ 🛠 wpe-skia
	🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	🛠 tv-sim		✅ 🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-commit-queue]

Committed 275749@main (095152b): https://commits.webkit.org/275749@main

Reviewed commits have been landed. Closing PR #25533 and removing active labels.