Roll Skia from bb9378b61c4f to 788fe69e7ade (6 revisions) (flutter#38226)

https://skia.googlesource.com/skia.git/+log/bb9378b61c4f..788fe69e7ade

2022-12-12 bsalomon@google.com Fix NaNs at 0 in ix_and_ptr() when rounding down.
2022-12-12 jvanverth@google.com [graphite] Add conditional context to UploadInstance
2022-12-12 nicolettep@google.com [graphite] Add VulkanBuffer map and unmap methods
2022-12-12 skia-autoroll@skia-public.iam.gserviceaccount.com Roll SwiftShader from 6a259c87ef52 to 5bd35e833079 (36 revisions)
2022-12-12 robertphillips@google.com [graphite] Minor key generation fixes
2022-12-12 skia-autoroll@skia-public.iam.gserviceaccount.com Roll vulkan-deps from 0ef5919fa702 to 8b5ea902f8d4 (1 revision)

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 bdero@google.com,johnstiles@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

Author: skia-flutter-autoroll

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': 'bb9378b61c4ff77044c84e816d305164a969a0db',
+  'skia_revision': '788fe69e7ade1b88ba76939a76694c9d19e86c5f',
 
   # WARNING: DO NOT EDIT canvaskit_cipd_instance MANUALLY
   # See `lib/web_ui/README.md` for how to roll CanvasKit to a new version.

ci/licenses_golden/licenses_skia

@@ -1,4 +1,4 @@
-Signature: b4f39ae9ce5bfa6887c8babed07ae3e5
+Signature: 8c27a1efbe9abe45441bb01b4ef718e8
 
 UNUSED LICENSES: