Roll Dart SDK from fa4b1e834d24 to 63c6585d8499 (2 revisions) (#24622)

DEPS

@@ -35,7 +35,7 @@ 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': 'fa4b1e834d24b752a3693e84c7915b5050c63d6e',
+  'dart_revision': '63c6585d849917a20aca415bc9df49cf97362b92',
 
   # 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: 6784deedf89522abb539e4be38698b4c
+Signature: 28f685a04d4d5cff3945a962d6c765a6
 
 UNUSED LICENSES: