Update XMLHttpRequest documentation.

lib/html/doc/interface/XMLHttpRequestProgressEvent.dartdoc

Index: lib/html/doc/interface/XMLHttpRequestProgressEvent.dartdoc
===================================================================
--- lib/html/doc/interface/XMLHttpRequestProgressEvent.dartdoc	(revision 11000)
+++ lib/html/doc/interface/XMLHttpRequestProgressEvent.dartdoc	(working copy)
@@ -1,17 +0,0 @@
-// Copyright (c) 2012, 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.
-
-/// @domName XMLHttpRequestProgressEvent
-interface XMLHttpRequestProgressEvent extends ProgressEvent {
-
-  /** @domName XMLHttpRequestProgressEvent.position */
-  final int position;
-
-  /** @domName XMLHttpRequestProgressEvent.totalSize */
-  final int totalSize;
-}