Roll Flutter Engine from 06696e768c1b to 8389ad914b21 (2 revisions) (#134469)

https://github.com/flutter/engine/compare/06696e768c1b...8389ad914b21

2023-09-11 109111084+yaakovschectman@users.noreply.github.com Merge `Window` into `FlutterWindow` (flutter/engine#45542)
2023-09-11 skia-flutter-autoroll@skia.org Roll Fuchsia Mac SDK from 7Zk_dvFh301kgQte4... to fSmVaZwp41ZGp5hKn... (flutter/engine#45665)

Also rolling transitive DEPS:
  fuchsia/sdk/core/mac-amd64 from 7Zk_dvFh301k to fSmVaZwp41ZG

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://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

bin/internal/engine.version

-06696e768c1b1abd2393099d4ccacfdff2ad4739
+8389ad914b21af99999c432fd04ba4c84d95e2fc

bin/internal/fuchsia-mac.version

-7Zk_dvFh301kgQte47pTgn_aAWmEVZ3YE4WFpXPQF2QC
+fSmVaZwp41ZGp5hKnDIGj56IAdgVpbpMTPwN21pR_DYC