Roll Dart SDK from dc20e31 to 4f5e556 (1 revision) (flutter#37056)

Author: skia-flutter-autoroll

DEPS

@@ -43,7 +43,7 @@ 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': 'dc20e31ba74c445dadd77fcc608311c69116cce9',
+  'dart_revision': '4f5e556d1e333ff9f3d470c236e86f42677edc8c',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py