Roll Skia from f67db9982729 to 21f4d4a4a025 (1 revision) (flutter/engine#54319)

https://skia.googlesource.com/skia.git/+log/f67db9982729..21f4d4a4a025

2024-08-02 kjlubick@google.com Remove legacy Dawn Graphite shims

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/skia-flutter-autoroll
Please CC brianosman@google.com,jacksongardner@google.com,johnstiles@google.com,rmistry@google.com on the revert to ensure that a human
is aware of the problem.

To file a bug in Skia: https://bugs.chromium.org/p/skia/issues/entry
To file a bug in Flutter: https://github.com/flutter/flutter/issues/new/choose

To report a problem with the AutoRoller itself, please file a bug:
https://issues.skia.org/issues/new?component=1389291&template=1850622

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

DEPS

@@ -14,7 +14,7 @@ vars = {
   'flutter_git': 'https://flutter.googlesource.com',
   'skia_git': 'https://skia.googlesource.com',
   'llvm_git': 'https://llvm.googlesource.com',
-  'skia_revision': 'f67db99827294bd3fc344d068dc2b121c23ced2f',
+  'skia_revision': '21f4d4a4a02538f173f9a5c8412f90c849982eba',
 
   # WARNING: DO NOT EDIT canvaskit_cipd_instance MANUALLY
   # See `lib/web_ui/README.md` for how to roll CanvasKit to a new version.

engine/src/flutter/ci/licenses_golden/licenses_skia

@@ -1,4 +1,4 @@
-Signature: dfeb97e8b7eb2de8afedc4cadffadfa8
+Signature: 19ab19da47f804ef763813430db02605
 
 ====================================================================================================
 LIBRARY: etc1