Roll Dart SDK from 4a10533a4dc8 to bcf68d22f0fa (1 revision) (#49329)

https://dart.googlesource.com/sdk.git/+log/4a10533a4dc8..bcf68d22f0fa

2023-12-21 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com Version 3.3.0-253.0.dev

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

To file a bug in Flutter Engine: 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

Author: skia-flutter-autoroll

DEPS

@@ -66,7 +66,7 @@ vars = {
   # 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': '4a10533a4dc836c77d6fe4f429d163642ff11f91',
+  'dart_revision': 'bcf68d22f0faf8c58e7af5bcd5a948d7ecb9e0ba',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py