Roll Skia from 2d531d020c26 to 794b6f9240a8 (3 revisions) (flutter/engine#42888)

https://skia.googlesource.com/skia.git/+log/2d531d020c26..794b6f9240a8

2023-06-15 robertphillips@google.com [graphite] Remove SkImageGenerator::makeTextureImage
2023-06-15 michaelludwig@google.com [skif] Fix morphology sksl to avoid switch fallthroughs
2023-06-15 nicolettep@google.com [graphite] Fix multisample state in Vulkan graphics pipeline

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,chinmaygarde@google.com,herb@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': '2d531d020c260d1761179b7145e4a9fd64db3219',
+  'skia_revision': '794b6f9240a885fd9488b2e2560a7e305414e478',
 
   # 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: 471fe578b288caff4974e1aca344a942
+Signature: 1fbb0aa22aed1500972e348917b68344
 
 ====================================================================================================
 LIBRARY: etc1