Support 'Conditional' idl attribute.

client/dom/generated/src/wrapping/_WebKitMutationObserverWrappingImplementation.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 _WebKitMutationObserverWrappingImplementation extends DOMWrapperBase implements WebKitMutationObserver {
-  _WebKitMutationObserverWrappingImplementation() : super() {}
-
-  static create__WebKitMutationObserverWrappingImplementation() native {
-    return new _WebKitMutationObserverWrappingImplementation();
-  }
-
-  void disconnect() {
-    _disconnect(this);
-    return;
-  }
-  static void _disconnect(receiver) native;
-
-  String get typeName() { return "WebKitMutationObserver"; }
-}