Roll Dart SDK from 3629a798353d to a461c2b3366d (1 revision) (#23699)

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': '3629a798353d6c8d642acc41e30f31e24a12af66',
+  'dart_revision': 'a461c2b3366d58217a621080a42219ceac338aee',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py

ci/licenses_golden/licenses_third_party

-Signature: d2cc8ac6da5f2f9979588619a3b2064c
+Signature: 6ab6853e129840f6b1d011ab91a11f41
 
 UNUSED LICENSES: