Inherit EventTarget interface instead of duplicating its code

Source/core/dom/WebKitNamedFlow.idl

 /*
  * Copyright (C) 2011 Adobe Systems Incorporated. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above
  *    copyright notice, this list of conditions and the following
  *    disclaimer.
@@ skipping 12 matching lines @@
  * 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.
  */
 
 [
     NoInterfaceObject,
     EnabledAtRuntime=cssRegions,
-    EventTarget,
     ImplementedAs=NamedFlow,
     GenerateIsReachable=ownerNode
-] interface WebKitNamedFlow {
+] interface WebKitNamedFlow : EventTarget {
     readonly attribute DOMString name;
     readonly attribute boolean overset;
     readonly attribute long firstEmptyRegionIndex;
     NodeList getRegionsByContent(Node contentNode);
     NodeList getRegions();
     NodeList getContent();
-
-    // EventTarget interface
-    void addEventListener(DOMString type, 
-                          EventListener listener, 
-                          optional boolean useCapture);
-    void removeEventListener(DOMString type, 
-                             EventListener listener, 
-                             optional boolean useCapture);
-    [RaisesException] boolean dispatchEvent(Event event);
 };