Revert "Roll Dart SDK from 3d4d29d8f16b to 9d8df2a5210b (2 revisions) (flutter#42509)"

This reverts commit 01209d9.

Author: zanderso

DEPS

@@ -53,7 +53,7 @@ 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': '9d8df2a5210b8888b1ef86eeb4235cebfcb4b578',
+  'dart_revision': '3d4d29d8f16b7d81c03b701f29039fb216d15a56',
 
   # 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

@@ -1,4 +1,5 @@
-Signature: 5fce067e90cfe2c74b5c556030912ef7
+Signature: 612472c74d11b7e55d45cafe6a7a8fde
+
 
 ====================================================================================================
 LIBRARY: angle