Inherit EventTarget interface instead of duplicating its code

Source/core/loader/appcache/DOMApplicationCache.idl

 /*
  * Copyright (C) 2008, 2009 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
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  *
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  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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 [
     NoInterfaceObject,
-    EventTarget,
     DoNotCheckConstants
-] interface DOMApplicationCache {
+] interface DOMApplicationCache : EventTarget {
     // update status
     const unsigned short UNCACHED = 0;
     const unsigned short IDLE = 1;
     const unsigned short CHECKING = 2;
     const unsigned short DOWNLOADING = 3;
     const unsigned short UPDATEREADY = 4;
     const unsigned short OBSOLETE = 5;
     readonly attribute unsigned short status;
 
     [RaisesException] void update();
     [RaisesException] void swapCache();
     void abort();
 
     // events
     attribute EventListener onchecking;
     attribute EventListener onerror;
     attribute EventListener onnoupdate;
     attribute EventListener ondownloading;
     attribute EventListener onprogress;
     attribute EventListener onupdateready;
     attribute EventListener oncached;
     attribute EventListener onobsolete;
-
-    // EventTarget interface
-    void addEventListener(DOMString type, 
-                          EventListener listener, 
-                          optional boolean useCapture);
-    void removeEventListener(DOMString type, 
-                             EventListener listener, 
-                             optional boolean useCapture);
-    [RaisesException] boolean dispatchEvent(Event evt);
 };