Roll src/third_party/dart 80fc4d54e5..24f1f313a2 (5 commits)

dart-lang/sdk@24f1f313a2 [cfe] Implement the rest of the NNBD-aware subtype relation
dart-lang/sdk@37d14ad2ce [ddk] Don't use Library.isExternal (second try)
dart-lang/sdk@fe3afde2eb [CFE] Parser: Don't report (recovered) operator as endClassConstructor
dart-lang/sdk@e1f19de968 [cfe] Add MemberBuilder.read/write/invokeTarget
dart-lang/sdk@239ff1408d [cfe] Add MemberBuilder.buildMembers

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': '80fc4d54e5246a1b63384fe26d72278f8c090b16',
+  'dart_revision': '24f1f313a22c6b83b9eb1abed01b83ee4f681057',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py