Remove deprecated_warning.

pkg/front_end/lib/src/fasta/source/stack_listener.dart

Index: pkg/front_end/lib/src/fasta/source/stack_listener.dart
diff --git a/pkg/front_end/lib/src/fasta/source/stack_listener.dart b/pkg/front_end/lib/src/fasta/source/stack_listener.dart
index eef8d924926302e49025c235721f64c1eca4d3c2..c34a4b2d77ce0f2ae0a89151f294f7e9b7d7e46c 100644
--- a/pkg/front_end/lib/src/fasta/source/stack_listener.dart
+++ b/pkg/front_end/lib/src/fasta/source/stack_listener.dart
@@ -276,10 +276,6 @@ abstract class StackListener extends Listener {
     messages.nit(message, charOffset, uri);
   }
 
-  void deprecated_warning(String message, [int charOffset = -1]) {
-    messages.deprecated_warning(uri, charOffset, message);
-  }
-
   void warning(Message message, int charOffset) {
     messages.warning(message, charOffset, uri);
   }