Roll src/third_party/dart 1e4a56ee7202..28eb884d4709 (1 commits) (#17513)

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': '1e4a56ee720218ae82af13a9cf71e038b0884cfc',
+  'dart_revision': '28eb884d4709e857764de5c2c4aac93a789311de',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py