Safely wrap window.top in frog dom.

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

 // 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 _DatabaseSyncWrappingImplementation extends DOMWrapperBase implements DatabaseSync {
   _DatabaseSyncWrappingImplementation() : super() {}
 
   static create__DatabaseSyncWrappingImplementation() native {
     return new _DatabaseSyncWrappingImplementation();
   }
 
   String get lastErrorMessage() { return _get_lastErrorMessage(this); }
   static String _get_lastErrorMessage(var _this) native;
 
   String get version() { return _get_version(this); }
   static String _get_version(var _this) native;
 
   void changeVersion(String oldVersion, String newVersion, [SQLTransactionSyncCallback callback = null]) {
-    if (callback === null) {
-      _changeVersion(this, oldVersion, newVersion);
-      return;
-    } else {
-      _changeVersion_2(this, oldVersion, newVersion, callback);
-      return;
-    }
+    _changeVersion(this, oldVersion, newVersion, callback);
+    return;
   }
-  static void _changeVersion(receiver, oldVersion, newVersion) native;
-  static void _changeVersion_2(receiver, oldVersion, newVersion, callback) native;
+  static void _changeVersion(receiver, oldVersion, newVersion, callback) native;
 
   void readTransaction(SQLTransactionSyncCallback callback) {
     _readTransaction(this, callback);
     return;
   }
   static void _readTransaction(receiver, callback) native;
 
   void transaction(SQLTransactionSyncCallback callback) {
     _transaction(this, callback);
     return;
   }
   static void _transaction(receiver, callback) native;
 
   String get typeName() { return "DatabaseSync"; }
 }