Inherit EventTarget interface instead of duplicating its code

Source/modules/mediastream/MediaStream.idl

 /*
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 [
     NoInterfaceObject,
-    EventTarget,
     Constructor,
     Constructor(MediaStream stream),
     Constructor(MediaStreamTrack[] tracks),
     ConstructorCallWith=ScriptExecutionContext
-] interface MediaStream {
+] interface MediaStream : EventTarget {
     // DEPRECATED
     readonly attribute DOMString label;
 
     readonly attribute DOMString id;
 
     sequence<MediaStreamTrack> getAudioTracks();
     sequence<MediaStreamTrack> getVideoTracks();
 
     [RaisesException] void addTrack(MediaStreamTrack track);
     [RaisesException] void removeTrack(MediaStreamTrack track);
     MediaStreamTrack getTrackById(DOMString trackId);
 
     readonly attribute boolean ended;
     void stop();
 
     attribute EventListener onended;
     attribute EventListener onaddtrack;
     attribute EventListener onremovetrack;
-
-    // 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);
 };