Roll Skia from 641994569415 to 42ff13a91c80 (8 revisions) (flutter#177283)

https://skia.googlesource.com/skia.git/+log/641994569415..42ff13a91c80

2025-10-20 mike@reedtribe.org Move path-contains impl into priv
2025-10-20 kjlubick@google.com Mark more single argument constructors
explicit
2025-10-20 fmalita@google.com Replace SkScalarAve with sk_float_midpoint
2025-10-20 kjlubick@google.com Add build docs about third_party needs
2025-10-20 mike@reedtribe.org Start migration off of pathref in SkPath
impl : spans
2025-10-20 mike@reedtribe.org Some SkPath cleanups
2025-10-20 kjlubick@google.com Cleanup in SkScan_antipath
2025-10-20 bungeman@google.com Directly initialize flags in
info_for_pixmap

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 codefu@google.com,jmbetancourt@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

@@ -15,7 +15,7 @@ vars = {
   'flutter_git': 'https://flutter.googlesource.com',
   'skia_git': 'https://skia.googlesource.com',
   'llvm_git': 'https://llvm.googlesource.com',
-  'skia_revision': '641994569415ae4ac2de895ea6da17073252e3dd',
+  'skia_revision': '42ff13a91c80fc8b6b6e808f0accea3871471e38',
 
   # WARNING: DO NOT EDIT canvaskit_cipd_instance MANUALLY
   # See `lib/web_ui/README.md` for how to roll CanvasKit to a new version.