Roll Dart SDK from e256855d07ba to a3b62f366529 (4 revisions) (#21808)

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': 'e256855d07ba9cad5048f012f38a05446ca2fe09',
+  'dart_revision': 'a3b62f366529dbe4e4e75b73124bc59581ce6428',
 
   # 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: 4f38a8a9ed9b09a6bd9f88ed98a9fe08
+Signature: d6984173aaddceb290a38b46fdf75c9c
 
 UNUSED LICENSES:
 
@@ -8115,6 +8115,7 @@ FILE: ../../../third_party/dart/runtime/vm/compiler/write_barrier_elimination.cc
 FILE: ../../../third_party/dart/runtime/vm/compiler/write_barrier_elimination.h
 FILE: ../../../third_party/dart/runtime/vm/compiler/write_barrier_elimination_test.cc
 FILE: ../../../third_party/dart/runtime/vm/constants_base.h
+FILE: ../../../third_party/dart/runtime/vm/datastream_test.cc
 FILE: ../../../third_party/dart/runtime/vm/dispatch_table.cc
 FILE: ../../../third_party/dart/runtime/vm/dispatch_table.h
 FILE: ../../../third_party/dart/runtime/vm/field_table.cc