Inherit EventTarget interface instead of duplicating its code

Source/modules/mediasource/MediaSource.idl

 /*
  * Copyright (C) 2013 Google 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 13 matching lines @@
  * 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.
  */
  
 [
     EnabledAtRuntime=mediaSource,
     ActiveDOMObject,
-    EventTarget,
     Constructor,
     ConstructorCallWith=ScriptExecutionContext
-] interface MediaSource {
+] interface MediaSource : EventTarget {
     // All the source buffers created by this object.
     readonly attribute SourceBufferList sourceBuffers;
 
     // Subset of sourceBuffers that provide data for the selected/enabled tracks.
     readonly attribute SourceBufferList activeSourceBuffers;
 
     [SetterRaisesException] attribute double duration;
 
     [RaisesException] SourceBuffer addSourceBuffer(DOMString type);
     [RaisesException] void removeSourceBuffer(SourceBuffer buffer);
 
     readonly attribute DOMString readyState;
     
     [RaisesException] void endOfStream([Default=NullString] optional DOMString error);
 
     static boolean isTypeSupported (DOMString type);
-
-    // 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);
 };