Roll Flutter Engine from fbb2b1e880fa to 9a840e8dba40 (1 revision) (#139192)

https://github.com/flutter/engine/compare/fbb2b1e880fa...9a840e8dba40

2023-11-29 98614782+auto-submit[bot]@users.noreply.github.com Reverts "binary_messenger missing cstdint" (flutter/engine#48483)

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 matanl@google.com,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

-fbb2b1e880fa52c427e293e1f34280d401bcf1e1
+9a840e8dba40fe7925aa1487bc972832dc167fdf