Roll Skia from 4e42b51cfe27 to 76898dad9fda (1 revision) (#45019)

https://skia.googlesource.com/skia.git/+log/4e42b51cfe27..76898dad9fda

2023-08-23 [email protected] Add unit test for bitmap-backed SkImage cache key extraction

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 [email protected],[email protected],[email protected],[email protected] 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://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

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

DEPS

@@ -18,7 +18,7 @@ vars = {
   'llvm_git': 'https://llvm.googlesource.com',
   # OCMock is for testing only so there is no google clone
   'ocmock_git': 'https://github.com/erikdoe/ocmock.git',
-  'skia_revision': '4e42b51cfe27717ddbe9f4ba568647fe3800ee12',
+  'skia_revision': '76898dad9fda119aa14b05fba18d32965c54015e',
 
   # WARNING: DO NOT EDIT canvaskit_cipd_instance MANUALLY
   # See `lib/web_ui/README.md` for how to roll CanvasKit to a new version.