Update XMLHttpRequest documentation.

lib/html/doc/interface/HttpRequest.dartdoc

Index: lib/html/doc/interface/HttpRequest.dartdoc
===================================================================
--- lib/html/doc/interface/HttpRequest.dartdoc	(revision 11000)
+++ lib/html/doc/interface/HttpRequest.dartdoc	(working copy)
@@ -6,18 +6,22 @@
 //   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;
 
@@ -57,7 +61,7 @@
   final String statusText;
 
   /** @domName XMLHttpRequest.upload */
-  final XMLHttpRequestUpload upload;
+  final HttpRequestUpload upload;
 
   /** @domName XMLHttpRequest.withCredentials */
   bool withCredentials;
@@ -93,7 +97,7 @@
   void setRequestHeader(String header, String value);
 }
 
-interface XMLHttpRequestEvents extends Events {
+interface HttpRequestEvents extends Events {
 
   EventListenerList get abort();