Revert "Roll src/third_party/dart f7902889b6..6e2b3f0326 (7 commits)" (#11298)

This reverts commit e9b4a595.

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': '6e2b3f0326bc15ad938319cbbb151f183d064609',
+  'dart_revision': 'f7902889b6e30a8b9d71416e1facf3c509aad06f',
 
   # 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: 5b79ad77f8b89f4b9c8c5a94fca653cb
+Signature: 8150fbd17d2122e7cb6fe8fcfb41d8d5
 
 UNUSED LICENSES: