Roll Dart SDK from 2d30896744b5 to a476002dba33 (2 revisions) (#24562)

https://dart.googlesource.com/sdk.git/+log/2d30896744b5..a476002dba33

2021-02-22 dart-luci-ci-builder@dart-ci.iam.gserviceaccount.com Version 2.13.0-63.0.dev
2021-02-22 dart-luci-ci-builder@dart-ci.iam.gserviceaccount.com Version 2.13.0-62.0.dev

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/dart-sdk-flutter-engine
Please CC dart-vm-team@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/master/autoroll/README.md

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': '2d30896744b5baf2e028ae549651eb7793fb554b',
+  'dart_revision': 'a476002dba33e27e0f82bb6fbfb9385685e8d943',
 
   # 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: 593ae7bcd7102bf82aad099b9c00170d
+Signature: 0d565b1d8854eb8456c33c4617c5f799
 
 UNUSED LICENSES: