Roll Skia from 256c15026b91 to 4a2fddefd3d8 (6 revisions) (#191633)

https://skia.googlesource.com/skia.git/+log/256c15026b91..4a2fddefd3d8

2026-08-25
recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com
Roll recipe dependencies (trivial).
2026-08-24
recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com
Roll recipe dependencies (trivial).
2026-08-24 skia-autoroll@skia-public.iam.gserviceaccount.com Roll
vulkan-deps from 7cc39635d2f5 to 21cfd4064773 (8 revisions)
2026-08-24
recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com
Roll recipe dependencies (trivial).
2026-08-24
recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com
Roll recipe dependencies (trivial).
2026-08-24 michaelludwig@google.com [skif] SkBlurEngine marks its
devices immutable when finished

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 awolff@google.com,fmalita@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