Roll Dart SDK from dfef9e3dc99b to dfe46b946c98 (1 revision) (#33390)

diff --git a/DEPS b/DEPS
index 14b91e8..dcc037a 100644
--- a/DEPS
+++ b/DEPS
@@ -45,7 +45,7 @@
   # Dart is: https://github.com/dart-lang/sdk/blob/main/DEPS.
   # You can use //tools/dart/create_updated_flutter_deps.py to produce
   # updated revision list of existing dependencies.
-  'dart_revision': 'dfef9e3dc99b8f86a151257eb7f264ab02171602',
+  'dart_revision': 'dfe46b946c98f705d299529d24b9043f545f9a50',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py