[flutter_releases] Flutter beta 3.16.0-0.4.pre Engine Cherrypicks (#47513)

# Flutter beta 3.16.0-0.4.pre Engine

## Scheduled Cherrypicks

- Roll dart revision: dart-lang/sdk@a30d2edb8

Author: Casey Hillers

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': '668bef34e453fc84ab9fa572d917110b51fa88eb',
+  'dart_revision': 'a30d2edb8118b3b19793931f7832c8f7260b3509',
 
   # 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_dart

@@ -1,4 +1,4 @@
-Signature: 405b8ee3823b5f5570f4fba28f153a5b
+Signature: 323f1797e915f510d400d94a16cacb78
 
 ====================================================================================================
 LIBRARY: dart