Roll Flutter Engine from f3496a7185c2 to 3fd9c4ee4fc0 (4 revisions) (#141037)

https://github.com/flutter/engine/compare/f3496a7185c2...3fd9c4ee4fc0

2024-01-05 skia-flutter-autoroll@skia.org Roll Skia from 548827f77466 to 9ec012033c2b (1 revision) (flutter/engine#49564)
2024-01-05 skia-flutter-autoroll@skia.org Roll Skia from a006922df1c5 to 548827f77466 (1 revision) (flutter/engine#49561)
2024-01-05 skia-flutter-autoroll@skia.org Roll Skia from 52be1b25c3a2 to a006922df1c5 (4 revisions) (flutter/engine#49559)
2024-01-05 dnfield@google.com Allow spawning additional UI isolates in flutter_tester (flutter/engine#48706)

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-engine-flutter-autoroll
Please CC rmistry@google.com,zra@google.com on the revert to ensure that a human
is aware of the problem.

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

bin/internal/engine.version

-f3496a7185c2e12fa895dbac553ec7ee8968b874
+3fd9c4ee4fc08a7504da7d04d7614302eb9b50db