Roll Skia from a7bcbb9a39f3 to 81b9c7fd19b2 (1 revision) (#46129)

https://skia.googlesource.com/skia.git/+log/a7bcbb9a39f3..81b9c7fd19b2

2023-09-21 [email protected] Roll SK Tool from 918412e0912f to af63cb4763f0

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

Author: skia-flutter-autoroll

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': 'a7bcbb9a39f38814919da9b7303a01c11207d031',
+  'skia_revision': '81b9c7fd19b23dd0b54a2d6fd4d8b07b3cedeee5',
 
   # WARNING: DO NOT EDIT canvaskit_cipd_instance MANUALLY
   # See `lib/web_ui/README.md` for how to roll CanvasKit to a new version.