Revert "Roll src/third_party/dart c359b59..bc93488 (1 commits) (flutter#15962)"

This reverts commit f66c5bb.

Author: NoamDev

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': 'bc9348829ef833c8dc91d6f13f847afa51c63947',
+  'dart_revision': 'c359b5943a52b525198bb094a731d06c2a7fe08f',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py