Roll Skia from 56de22c39d0e to 20e4dfabb6b2 (1 revision) (flutter/engine#54205)

https://skia.googlesource.com/skia.git/+log/56de22c39d0e..20e4dfabb6b2

2024-07-30 bsheedy@chromium.org Revert "[graphite] Read aggregate SSBO once in main()"

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,jonahwilliams@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': '56de22c39d0ed5601175f8f4cee72233864be72b',
+  'skia_revision': '20e4dfabb6b2dbca6ef342aec837072ed2e12fe7',
 
   # 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: 9c282e6e7f6e46aee621795ea5b6e009
+Signature: 30182e9edb97c546e82366a8a82acdae
 
 ====================================================================================================
 LIBRARY: etc1