Roll src/third_party/dart 9aea1f3489..b9217efc77 (7 commits)

dart-lang/sdk@b9217efc77 [CFE] [Language versioning] Issue error on multiple 'dart=' entries
dart-lang/sdk@e47f354919 Allow ddc in kernel mode to output used inputs
dart-lang/sdk@aeb864a43f Allow bazels kernel_worker to output used inputs
dart-lang/sdk@38336d6b5a [CFE] Split spell dictionary into several different dictionaries
dart-lang/sdk@b8f1b8987e Extract TypeArgumentsVerifier.
dart-lang/sdk@9ed7471aaf [nnbd_migration] Add api test for how we don't plan to handle postdominators of cfg edits
dart-lang/sdk@78efb23609 Fix typo in comment on GLB

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': '9aea1f3489e2fce0efab6121f3060c8ce890ae89',
+  'dart_revision': 'b9217efc77a4979f80957296f015841ea65b9d59',
 
   # 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: 14ecb78fd1d5eb2f001a2e055c85ac94
+Signature: 868c55ecd7ce754257283e8479a3fcbf
 
 UNUSED LICENSES: