Roll Skia from 844496884aa0 to 6c4595124690 (2 revisions) (flutter#167400)

https://skia.googlesource.com/skia.git/+log/844496884aa0..6c4595124690

2025-04-18 skia-autoroll@skia-public.iam.gserviceaccount.com Roll
vulkan-deps from da64cc98aa1f to b61587033344 (1 revision)
2025-04-18 skia-autoroll@skia-public.iam.gserviceaccount.com Roll ANGLE
from a6a7de5aecab to 4b9525b2667f (7 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 bwils@google.com,codefu@google.com,kjlubick@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

Author: engine-flutter-autoroll

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': '844496884aa06d283d92f096a523e9587f5f8c36',
+  'skia_revision': '6c4595124690ceac380cf80c3edbb78036ded1ef',
 
   # WARNING: DO NOT EDIT canvaskit_cipd_instance MANUALLY
   # See `lib/web_ui/README.md` for how to roll CanvasKit to a new version.