Roll Dart SDK from ba50855 to f2b0d38 (1 revision)

https://dart.googlesource.com/sdk.git/+log/ba50855227b3..f2b0d387684d

2021-08-18 dart-luci-ci-builder@dart-ci.iam.gserviceaccount.com Version 2.15.0-25.0.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,zra@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

@@ -39,7 +39,7 @@ vars = {
   # Dart is: https://github.com/dart-lang/sdk/blob/master/DEPS.
   # You can use //tools/dart/create_updated_flutter_deps.py to produce
   # updated revision list of existing dependencies.
-  'dart_revision': 'ba50855227b38612a011aaf3d651c1e0e2aa1e4c',
+  'dart_revision': 'f2b0d387684d62383b24bb802fae829f24f658d9',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py