Roll Flutter Engine from f539acfb8c5a to b81023eb71c9 (1 revision) (#140973)

https://github.com/flutter/engine/compare/f539acfb8c5a...b81023eb71c9

2024-01-04 skia-flutter-autoroll@skia.org Manual roll Dart SDK from 7e9f7eab80d3 to 7f2523c2fa9a (3 revisions) (flutter/engine#49534)

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

-f539acfb8c5a07b6317bdfdc22588cc1ed125ae7
+b81023eb71c97fcf28f4072cc2d990c47860f520