Roll Dart SDK from d61b089bb5c6 to edc28e4a5236 (1 revision) (#20578)

diff --git a/DEPS b/DEPS
index 8ce81ac..cb20705 100644
--- a/DEPS
+++ b/DEPS
@@ -34,7 +34,7 @@
   # 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': 'd61b089bb5c6154be6dd7ede5746237d85591ff0',
+  'dart_revision': 'edc28e4a5236359d7508318a1ad69959912faace',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py
@@ -226,7 +226,7 @@
    Var('dart_git') + '/intl.git' + '@' + Var('dart_intl_tag'),
 
   'src/third_party/dart/third_party/pkg/json_rpc_2':
-   Var('dart_git') + '/json_rpc_2.git@413ee9d1d1841c23ebfd2248abc4fc950e0d6946',
+   Var('dart_git') + '/json_rpc_2.git@995611cf006c927d51cc53cb28f1aa4356d5414f',
 
   'src/third_party/dart/third_party/pkg/linter':
    Var('dart_git') + '/linter.git' + '@' + Var('dart_linter_tag'),
@@ -235,7 +235,7 @@
    Var('dart_git') + '/logging.git@9561ba016ae607747ae69b846c0e10958ca58ed4',
 
   'src/third_party/dart/third_party/pkg/markdown':
-   Var('dart_git') + '/markdown.git@acaddfe74217f62498b5cf0cf5429efa6a700be3',
+   Var('dart_git') + '/markdown.git@dbeafd47759e7dd0a167602153bb9c49fb5e5fe7',
 
   'src/third_party/dart/third_party/pkg/matcher':
    Var('dart_git') + '/matcher.git@9cae8faa7868bf3a88a7ba45eb0bd128e66ac515',
diff --git a/ci/licenses_golden/licenses_third_party b/ci/licenses_golden/licenses_third_party
index 9ce7eeb..917e99e 100644
--- a/ci/licenses_golden/licenses_third_party
+++ b/ci/licenses_golden/licenses_third_party
@@ -1,4 +1,4 @@
-Signature: 769562cf74b1ccde2ad9c6d9a28000fc
+Signature: 3ca48237444128057b7f6143e558dd11
 
 UNUSED LICENSES: