Roll src/third_party/dart aece1c1e92..f4a72bfc64 (4 commits)

dart-lang/sdk@f4a72bfc64 [cfe] Don't crash on access to extension fields
dart-lang/sdk@41c11716b0 [kernel] Make round-trip script work; improve fastas compare dill tool
dart-lang/sdk@9276d50fdc [cfe] Remove Severity.errorLegacyWarning
dart-lang/sdk@bc8b12e43b [cfe] Handle privacy in extension lookup

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': 'aece1c1e927341c1c9b6517cc7d668974280de98',
+  'dart_revision': 'f4a72bfc646c47a6a1639725b406a4eda19a870f',
 
   # 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: 25e2b30226f59acec59cad73d452e693
+Signature: cdea1bbd556ea7577323fe5ef947b6b0
 
 UNUSED LICENSES: