Roll Dart SDK from 2a5f37d25453 to e8e0d5a539fb (3 revisions) (#20928)

Author: skia-flutter-autoroll

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': '2a5f37d2545304b1065bf9a6e6cc42f5e88c772a',
+  'dart_revision': 'e8e0d5a539fb3e7296ed674216ce05aa1d053dd1',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py