Introduce XMLHttpRequestEventTarget IDL interface

Source/core/xml/XMLHttpRequest.idl

 /*
  * Copyright (C) 2008, 2011 Apple 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 24 matching lines @@
 //    "json",
     "text"
 };
 
 [
     GlobalContext=Window&WorkerGlobalScope,
     ActiveDOMObject,
     Constructor,
     ConstructorCallWith=ScriptExecutionContext,
     CustomConstructor(optional XMLHttpRequestOptions options)
-] interface XMLHttpRequest : EventTarget {
-    // From XMLHttpRequestEventTarget
-    // event handler attributes
-    attribute EventHandler onabort;
-    attribute EventHandler onerror;
-    attribute EventHandler onload;
-    attribute EventHandler onloadend;
-    attribute EventHandler onloadstart;
-    attribute EventHandler onprogress;
-    attribute EventHandler ontimeout;
-
+] interface XMLHttpRequest : XMLHttpRequestEventTarget {
     // event handler attributes
     attribute EventHandler onreadystatechange;
 
     // state
     const unsigned short UNSENT = 0;
     const unsigned short OPENED = 1;
     const unsigned short HEADERS_RECEIVED = 2;
     const unsigned short LOADING = 3;
     const unsigned short DONE = 4;
 
@@ skipping 20 matching lines @@
 
     [SetterRaisesException] attribute XMLHttpRequestResponseType responseType;
     [CustomGetter, GetterRaisesException] readonly attribute Object response;
 
     [GetterRaisesException] readonly attribute unsigned short status;
     [GetterRaisesException] readonly attribute DOMString statusText;
 
     // Extension
     void overrideMimeType(DOMString override);
 };