Roll Dart SDK from b3bc5acdeef2 to f209e60a5415 (2 revisions) (#24722)

diff --git a/DEPS b/DEPS
index ba64ec0..1298f94 100644
--- a/DEPS
+++ b/DEPS
@@ -35,7 +35,7 @@
   # 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': 'b3bc5acdeef27a020d74800802921b96bf33bc80',
+  'dart_revision': 'f209e60a5415397b7c773c6f06570c3dde844999',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py
@@ -189,7 +189,7 @@
    Var('dart_git') + '/dart2js_info.git@e0acfeb5affdf94c53067e68bd836adf589628fd',
 
   'src/third_party/dart/third_party/pkg/dartdoc':
-   Var('dart_git') + '/dartdoc.git@9e61a4f11091aaa8998525a2692b14148dc24ab5',
+   Var('dart_git') + '/dartdoc.git@174021f3d76c2a8500b54977c80f32c5bbc099f1',
 
   'src/third_party/dart/third_party/pkg/ffi':
    Var('dart_git') + '/ffi.git@f3346299c55669cc0db48afae85b8110088bf8da',
diff --git a/ci/licenses_golden/licenses_third_party b/ci/licenses_golden/licenses_third_party
index 2464338..3eb02d3 100644
--- a/ci/licenses_golden/licenses_third_party
+++ b/ci/licenses_golden/licenses_third_party
@@ -1,4 +1,4 @@
-Signature: f2936bdf8c5d9df38f895f5f0b87b18e
+Signature: bad21126f3fbac120b84c46fa6f554eb
 
 UNUSED LICENSES: