Roll Dart SDK from 9b3b9c26a343 to 83365979ea85 (1 revision) (flutter#21222)

Author: skia-flutter-autoroll

DEPS

@@ -34,7 +34,7 @@ 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': '9b3b9c26a343ef6ea48590921306dc32daa354ec',
+  'dart_revision': '83365979ea856fd8c755be7ee0b9a4dae0fb8db5',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py