Roll Dart SDK from b2550fec823c to 689440e4d163 (1 revision)

https://dart.googlesource.com/sdk.git/+log/b2550fec823c..689440e4d163

2023-03-10 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com Version 3.0.0-320.0.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 aam@google.com,dart-vm-team@google.com,jimgraham@google.com,rmistry@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

Author: skia-flutter-autoroll

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': 'b2550fec823cf59b36b18fe6d94a6ffe3ebe4980',
+  'dart_revision': '689440e4d16326ed59fe8d7185a81ce1402a4430',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py