Always set content length to 0 on redirect requests

sdk/lib/io/http_impl.dart

-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2013, 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.
 
 part of dart.io;
 
 // The close queue handles graceful closing of HTTP connections. When
 // a connection is added to the queue it will enter a wait state
 // waiting for all data written and possibly socket shutdown from
 // peer.
 class _CloseQueue {
@@ skipping 1669 matching lines @@
     }
     _redirects.add(redirect);
     _doRetry(redirect);
   }
 
   void redirect([String method, Uri url]) {
     if (method == null) method = _method;
     if (url == null) {
       url = new Uri.fromString(_response.headers.value(HttpHeaders.LOCATION));
     }
+    // Always set the content length to 0 for redirects.
+    var mutable = _request._headers._mutable;
+    _request._headers._mutable = true;
+    _request._headers.contentLength = 0;
+    _request._headers._mutable = mutable;
+    _request._bodyBytesWritten = 0;
     var redirect = new _RedirectInfo(_response.statusCode, method, url);
     // The actual redirect is postponed until both response and
     // request are done.
     assert(_pendingRetry == null);
     _pendingRedirect = redirect;
   }
 
   List<RedirectInfo> get redirects => _redirects;
 
   Function _onRequest;
@@ skipping 599 matching lines @@
 
 
 class _RedirectInfo implements RedirectInfo {
   const _RedirectInfo(int this.statusCode,
                       String this.method,
                       Uri this.location);
   final int statusCode;
   final String method;
   final Uri location;
 }