Fix issus 8828

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;
 
 class _HttpIncoming
     extends Stream<List<int>> implements StreamSink<List<int>> {
   final int _transferLength;
   final Completer _dataCompleter = new Completer();
@@ skipping 328 matching lines @@
     if (_ignoreBody) return new Future.immediate(this);
     if (_chunked) {
       // Transform when chunked.
       stream = stream.transform(new _ChunkedTransformer());
     }
     return super.consume(stream).then((_) => this);
   }
 
   void add(List<int> data) {
     _writeHeaders();
-    if (_ignoreBody) return;
+    if (_ignoreBody || data.length == 0) return;
     if (_chunked) {
       _ChunkedTransformer._addChunk(data, super.add);
     } else {
       super.add(data);
     }
   }
 
   void close() {
     if (!_headersWritten && !_ignoreBody && headers.chunkedTransferEncoding) {
       // If no body was written, _ignoreBody is false (it's not a HEAD
@@ skipping 1241 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;
 }