Roll Dart SDK from 442614a6c1bb to 6340d946feac (1 revision) (flutter…

…#38489)

https://dart.googlesource.com/sdk.git/+log/442614a6c1bb..6340d946feac

2022-12-23 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com Version 3.0.0-63.0.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 chinmaygarde@google.com,dart-vm-team@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://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

DEPS

@@ -48,7 +48,7 @@ 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': '442614a6c1bbd77b0a8ca4b012a97ad11d1aa745',
+  'dart_revision': '6340d946feac4651a4b13dc30535d7017ee6c3f0',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py