Roll Dart SDK from 75f6ccb9bdc5 to 020988602772 (1 revision) (flutter#177421)

https://dart.googlesource.com/sdk.git/+log/75f6ccb9bdc5..020988602772

2025-10-22 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com
Version 3.11.0-49.0.dev

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Author: engine-flutter-autoroll

DEPS

@@ -57,7 +57,7 @@ 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': '75f6ccb9bdc581ce428742dbc6872ae0847db8bf',
+  'dart_revision': '0209886027726944616043acd0592fb3888b4573',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py