Update XMLHttpRequest documentation.

lib/html/doc/interface/HttpRequest.dartdoc

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // WARNING:
 //   This file contains documentation that is merged into the real source.
 //   Do not make code changes here.
 
+/**
+ * HttpRequest is Dart's name for the XMLHttpRequest object, as described below.
+ */
+
 /// @domName XMLHttpRequest
-interface XMLHttpRequest extends EventTarget default _XMLHttpRequestFactoryProvider {
+interface HttpRequest extends EventTarget default _XMLHttpRequestFactoryProvider {
   // TODO(rnystrom): This name should just be "get" which is valid in Dart, but
   // not correctly implemented yet. (b/4970173)
-  XMLHttpRequest.get(String url, onSuccess(XMLHttpRequest request));
+  HttpRequest.get(String url, onSuccess(HttpRequest request));
 
-  XMLHttpRequest();
+  HttpRequest();
 
   /**
    * @domName EventTarget.addEventListener, EventTarget.removeEventListener, EventTarget.dispatchEvent
    */
-  XMLHttpRequestEvents get on();
+  HttpRequestEvents get on();
 
   static final int DONE = 4;
 
   static final int HEADERS_RECEIVED = 2;
 
   static final int LOADING = 3;
 
   static final int OPENED = 1;
 
   static final int UNSENT = 0;
@@ skipping 19 matching lines @@
   /** @domName XMLHttpRequest.responseXML */
   final Document responseXML;
 
   /** @domName XMLHttpRequest.status */
   final int status;
 
   /** @domName XMLHttpRequest.statusText */
   final String statusText;
 
   /** @domName XMLHttpRequest.upload */
-  final XMLHttpRequestUpload upload;
+  final HttpRequestUpload upload;
 
   /** @domName XMLHttpRequest.withCredentials */
   bool withCredentials;
 
   /** @domName XMLHttpRequest.abort */
   void abort();
 
   /** @domName XMLHttpRequest.addEventListener */
   void $dom_addEventListener(String type, EventListener listener, [bool useCapture]);
 
@@ skipping 15 matching lines @@
   /** @domName XMLHttpRequest.removeEventListener */
   void $dom_removeEventListener(String type, EventListener listener, [bool useCapture]);
 
   /** @domName XMLHttpRequest.send */
   void send([data]);
 
   /** @domName XMLHttpRequest.setRequestHeader */
   void setRequestHeader(String header, String value);
 }
 
-interface XMLHttpRequestEvents extends Events {
+interface HttpRequestEvents extends Events {
 
   EventListenerList get abort();
 
   EventListenerList get error();
 
   EventListenerList get load();
 
   EventListenerList get loadEnd();
 
   EventListenerList get loadStart();
 
   EventListenerList get progress();
 
   EventListenerList get readyStateChange();
 }