Roll src/third_party/dart 62f78a7abb..300c3333d1 (6 commits)

dart-lang/sdk@300c3333d1 [gardening] Always tag class_id register on arm64 in subtype test cache stub
dart-lang/sdk@6717bfe423 [vm/concurrency] Lock weak table to prepare for concurrent access.
dart-lang/sdk@8329968192 fix for prefer_single_quotes
dart-lang/sdk@9357b48a8d [gardening] Use target::kWordSizeLog2 instead of kWordSizeLog2 on arm (fixes broken build)
dart-lang/sdk@ef9d699f07 [vm/concurrency] Move all information except for the class pointers out of [ClassTable] into [SharedClassTable]
dart-lang/sdk@9a2e2801d9 fix for avoid_relative_lib_imports

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': '62f78a7abbece17678f7c63feba563ead9cb0749',
+  'dart_revision': '300c3333d17676fb45638963b3cb9086972bf3cc',
 
   # 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: 58b0be59b72058c207514003e3b11c14
+Signature: 1d180d64741ad59164c869782c120442
 
 UNUSED LICENSES: