Roll Dart SDK from 21aa7f8cbde8 to 90993fcb8554 (1 revision) (#25832)

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': '21aa7f8cbde83eb1d1b6bc9ec87b9ef5a19a76b3',
+  'dart_revision': '90993fcb85549f4f6fdaa8d0d4b79e8a4730ceb6',
 
   # 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: 85c4ef471460bebeb33d1bd300e3dab2
+Signature: 59549c91253b9a235299ac27e0f9cfdc
 
 UNUSED LICENSES: