Revert dart rolls (#26714)

* Revert "Roll Dart SDK from c8a66f8e7ca1 to 935470ea59c4 (1 revision) (#26707)"

This reverts commit 6ddc1488.

* Revert "Roll Dart SDK from d622b98e77d7 to c8a66f8e7ca1 (1 revision) (#26703)"

This reverts commit 1428214a.

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': '935470ea59c4cc573bad181014cd7e60bbba78d6',
+  'dart_revision': 'd622b98e77d744f1c8bf11b655f7288f12ffdd30',
 
   # 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: 6d1c5b197b54b9f1b148c009da8dd15b
+Signature: 2ea93a733f556d9a3a74e66512a69855
 
 UNUSED LICENSES: