Roll Dart SDK from ab8eafda59f7 to ec56a51b9cdd (1 revision) (flutter#33991)

Author: skia-flutter-autoroll

DEPS

@@ -45,7 +45,7 @@ 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': 'ab8eafda59f77cd316a2bdae961e39d0a50d4dce',
+  'dart_revision': 'ec56a51b9cdd5df34924bbd292186447d9a26ce6',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py