Roll Dart SDK from f8ff12008e84 to 8afe9875a6d7 (1 revision) (#19472)

diff --git a/DEPS b/DEPS
index 4bd4842..a9ed567 100644
--- a/DEPS
+++ b/DEPS
@@ -34,7 +34,7 @@
   # 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': 'f8ff12008e84c84fe93d44b7edf137328405b93b',
+  'dart_revision': '8afe9875a6d7acc2a002e2aad58de0934537387a',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py