Roll src/third_party/dart 19fc101..2a13b1f (6 commits) (flutter#14107)

dart-lang/sdk@2a13b1fe26 Reland "[dartdevc] Break dart:_debugger dependency on dart:html"
dart-lang/sdk@48573044b3 Replace helper methods in AbstractTypeSystemTest with ElementsTypesMixin.
dart-lang/sdk@7a911ce3f1 [ package:vm_service ] Fix issue where an exception could be thrown if remote service protocl version was older than that supported by package:vm_service
dart-lang/sdk@f4e44dd705 [vm] Make kernel buffers live exactly as long as their derived views.
dart-lang/sdk@5ecfd7058a Drop fallback to looser as check
dart-lang/sdk@9c220059a1 Implement DOWN for FunctionType(s) with NNBD rules.

Author: bkonyi

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': '19fc1016da374ac2dac2393a4f61d670b7860963',
+  'dart_revision': '2a13b1fe2699eab55c1e25742dc8e1c1501bf486',
 
   # 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

@@ -1,4 +1,4 @@
-Signature: 144c047a35c6bd7b19d2fff30cf2ad9f
+Signature: 88d6da4b86d1b10cb93b13653483c196
 
 UNUSED LICENSES: