Generate callbacks as typedefs.

client/dom/generated/src/wrapping/_StringCallbackWrappingImplementation.dart

Index: client/dom/generated/src/wrapping/_StringCallbackWrappingImplementation.dart
diff --git a/client/dom/generated/src/wrapping/_StringCallbackWrappingImplementation.dart b/client/dom/generated/src/wrapping/_StringCallbackWrappingImplementation.dart
deleted file mode 100644
index ae157ba9a153b6f63f99c8bcc18754bc449dc17a..0000000000000000000000000000000000000000
--- a/client/dom/generated/src/wrapping/_StringCallbackWrappingImplementation.dart
+++ /dev/null
@@ -1,20 +0,0 @@
-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-// WARNING: Do not edit - generated code.
-
-class _StringCallbackWrappingImplementation extends DOMWrapperBase implements StringCallback {
-  _StringCallbackWrappingImplementation() : super() {}
-
-  static create__StringCallbackWrappingImplementation() native {
-    return new _StringCallbackWrappingImplementation();
-  }
-
-  bool handleEvent(String data) {
-    return _handleEvent(this, data);
-  }
-  static bool _handleEvent(receiver, data) native;
-
-  String get typeName() { return "StringCallback"; }
-}