Roll Skia from e1b27dcecd0a to 818f20f3f653 (2 revisions) (flutter/engine#45353)

https://skia.googlesource.com/skia.git/+log/e1b27dcecd0a..818f20f3f653

2023-08-31 robertphillips@google.com Check for a valid ProxyCache in ResourceCache::purgeResources
2023-08-31 skia-autoroll@skia-public.iam.gserviceaccount.com Roll vulkan-deps from 557268622720 to 90907540b014 (4 revisions)

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 aaclarke@google.com,brianosman@google.com,jlavrova@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://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': 'e1b27dcecd0a8b0c2e2fcd5acde610c32010b739',
+  'skia_revision': '818f20f3f65350f44ada1fbcc20cc3e828c65ba9',
 
   # 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: 375c1110a309b921a27d08990052fce1
+Signature: 95f17b4b086bd2bcfcdfe008c80c297c
 
 ====================================================================================================
 LIBRARY: etc1