[flutter_releases] Flutter beta 3.9.0-0.2.pre Engine Cherrypicks (#40539)

* Update Dart SDK to 8cbaf6bff9bf78d7c970d68289721140bb1f14aa

* empty commit
diff --git a/DEPS b/DEPS
index 3e0f174..9c6cc41 100644
--- a/DEPS
+++ b/DEPS
@@ -48,7 +48,7 @@
   # Dart is: https://github.com/dart-lang/sdk/blob/main/DEPS
   # You can use //tools/dart/create_updated_flutter_deps.py to produce
   # updated revision list of existing dependencies.
-  'dart_revision': 'adb3e344cd0412e9505c29f14b89ceffede843c6',
+  'dart_revision': '8cbaf6bff9bf78d7c970d68289721140bb1f14aa',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py