Roll Dart SDK from 616f110ef95a to c7c4495b38ea (1 revision) (flutter#24967)

Author: skia-flutter-autoroll

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': '616f110ef95a40ae2ab49bfe04e0b8984cb716a5',
+  'dart_revision': 'c7c4495b38eae9b40ee170baca4634a8f4beacdb',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py