Notification should not leak document.

Source/modules/notifications/Notification.idl

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2011, 2012 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 13 matching lines @@
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 [
     Conditional=NOTIFICATIONS|LEGACY_NOTIFICATIONS,
-    ActiveDOMObject,
     Constructor(DOMString title, [Default=Undefined] optional Dictionary options),
     ConstructorCallWith=ScriptExecutionContext,
 ] interface Notification : EventTarget {
     void show();
     [Conditional=LEGACY_NOTIFICATIONS] void cancel();
     [Conditional=NOTIFICATIONS] void close();
 
 
     [CallWith=ScriptExecutionContext, Conditional=NOTIFICATIONS] static readonly attribute DOMString permission;
     [CallWith=ScriptExecutionContext, Conditional=NOTIFICATIONS] static void requestPermission(optional NotificationPermissionCallback callback);
 
     attribute EventHandler onshow;
     [Conditional=LEGACY_NOTIFICATIONS] attribute EventHandler ondisplay;
     attribute EventHandler onerror;
     attribute EventHandler onclose;
     attribute EventHandler onclick;
 
     [Conditional=LEGACY_NOTIFICATIONS] attribute DOMString dir;
     [Conditional=LEGACY_NOTIFICATIONS] attribute DOMString replaceId;
     [Conditional=NOTIFICATIONS] attribute DOMString tag;
 };