Roll Dart SDK from ba50855227b3 to f2b0d387684d (1 revision) (flutter#28154)

Author: skia-flutter-autoroll

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