Roll Skia from b50d7f9aa743 to 8dc8e21a4dec (4 revisions) (flutter/engine#46902)

https://skia.googlesource.com/skia.git/+log/b50d7f9aa743..8dc8e21a4dec

2023-10-13 skia-autoroll@skia-public.iam.gserviceaccount.com Roll skottie-base from bbf6a30f67f4 to 444eb9b78e14
2023-10-13 johnstiles@google.com Prefer precision over performance in Raster Pipeline.
2023-10-13 jvanverth@google.com [graphite] Enable RasterPathAtlas for single-sampled draws.
2023-10-13 johnstiles@google.com Enable Graphite in Canvaskit when WebGPU is enabled.

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,johnstiles@google.com,jsimmons@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

@@ -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': 'b50d7f9aa743e84abc1edb3177d8913f71286ec6',
+  'skia_revision': '8dc8e21a4dec559d26d3d71b80fc3ef82defcd5f',
 
   # 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: 3c5eda28fe39ef74efe5dd67bf6d469a
+Signature: 8120bfbac4bf0b1bb19c750a9e354f75
 
 ====================================================================================================
 LIBRARY: etc1