Throw an error when we redirect on a non-persistent connection.

sdk/lib/io/http_impl.dart

 // 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.
@@ skipping 1341 matching lines @@
         // Check for redirect loop
         if (_connection._redirects != null) {
           Uri redirectUrl = Uri.parse(location[0]);
           for (int i = 0; i < _connection._redirects.length; i++) {
             if (_connection._redirects[i].location.toString() ==
                 redirectUrl.toString()) {
               throw new RedirectLoopException(_connection._redirects);
             }
           }
         }
+        if (!persistentConnection) {
+          throw new RedirectException(
+              "Non-persistent connections are currently not supported for "
+              "redirects", _connection._redirects);
+        }
         // Drain body and redirect.
         inputStream.onData = inputStream.read;
         if (_statusCode == HttpStatus.SEE_OTHER &&
             _connection._method == "POST") {
           _connection.redirect("GET");
         } else {
           _connection.redirect();
         }
       } else {
         throw new RedirectLimitExceededException(_connection._redirects);
@@ skipping 953 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;
 }