Inherit EventTarget interface instead of duplicating its code

Source/modules/mediastream/RTCPeerConnection.idl

 /*
  * Copyright (C) 2012 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:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 15 matching lines @@
  * 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,
     ActiveDOMObject,
     Constructor(Dictionary rtcIceServers, optional Dictionary mediaConstraints),
     ConstructorRaisesException,
-    ConstructorCallWith=ScriptExecutionContext,
-    EventTarget
-] interface RTCPeerConnection {
+    ConstructorCallWith=ScriptExecutionContext
+] interface RTCPeerConnection : EventTarget {
     [RaisesException] void createOffer(RTCSessionDescriptionCallback successCallback, [Default=Undefined] optional RTCErrorCallback failureCallback, optional Dictionary mediaConstraints);
 
     [RaisesException] void createAnswer(RTCSessionDescriptionCallback successCallback, [Default=Undefined] optional RTCErrorCallback failureCallback, optional Dictionary mediaConstraints);
 
     [RaisesException] void setLocalDescription(RTCSessionDescription description, [Default=Undefined] optional VoidCallback successCallback, [Default=Undefined] optional RTCErrorCallback failureCallback);
     [GetterRaisesException] readonly attribute RTCSessionDescription localDescription;
 
     [RaisesException] void setRemoteDescription(RTCSessionDescription description, [Default=Undefined] optional VoidCallback successCallback, [Default=Undefined] optional RTCErrorCallback failureCallback);
     [GetterRaisesException] readonly attribute RTCSessionDescription remoteDescription;
 
@@ skipping 21 matching lines @@
 
     [RaisesException] void close();
 
     attribute EventListener onnegotiationneeded;
     attribute EventListener onicecandidate;
     attribute EventListener onsignalingstatechange;
     attribute EventListener onaddstream;
     attribute EventListener onremovestream;
     attribute EventListener oniceconnectionstatechange;
     attribute EventListener ondatachannel;
-
-    // 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);
 };