Fix signature of toStringName()
...which I accidentally changed in a previous commit.
diff --git a/packages/flutter/lib/src/widgets/framework.dart b/packages/flutter/lib/src/widgets/framework.dart
index 8468d31..7b887a2 100644
--- a/packages/flutter/lib/src/widgets/framework.dart
+++ b/packages/flutter/lib/src/widgets/framework.dart
@@ -945,7 +945,7 @@
     _scheduleBuild();
   }
 
-  String toStringName([String prefix = '', String startPrefix = '']) {
+  String toStringName() {
     if (_disqualifiedFromEverAppearingAgain)
       return '[[DISQUALIFIED]] ${super.toStringName()}';
     return super.toStringName();