Roll Dart SDK from 86d1f3b6a97c to 39424b348c44 (2 revisions) (#24605)

DEPS

@@ -35,7 +35,7 @@ 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': '86d1f3b6a97cffff0da3d0f2857f191f814c2631',
+  'dart_revision': '39424b348c442476ceaf445098475f730f09dcdb',
 
   # 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: a862115c02056898935fd5ab936c0171
+Signature: b23297d448712a7278961709447efcc6
 
 UNUSED LICENSES: