anchor.diff:      var uri = userString.substring(_DART_EXT.length);
       return '$_DART_EXT${baseUri.resolve(uri)}';
     } else {
  -    return '${baseUri.resolve(userString)}';
  +    return baseUri.resolve(userString).toString();
     }
   }
   
  
positive.code:                  "${_numOutstandingLoadRequests} requests remaining");
    if (_numOutstandingLoadRequests == 0) {
      _signalDoneLoading();
    }
  }
  
  
negative.code: 
  
  int _numOutstandingLoadRequests = 0;
  var _httpClient;
  
  void _httpGet(Uri uri, String libraryUri, loadCallback(List<int> data)) {
    if (_httpClient == null) {
      _httpClient = new HttpClient()..maxConnectionsPerHost = 6;
    }
    _httpClient.getUrl(uri)
      .then((HttpClientRequest request) => request.close())
      .then((HttpClientResponse response) {
        var builder = new BytesBuilder(copy: false);
        response.listen(
            builder.add,
            onDone: () {
              if (response.statusCode != 200) {
                var msg = 'Failure getting $uri: '
                          '${response.statusCode} ${response.reasonPhrase}';
                _asyncLoadError(uri.toString(), libraryUri, msg);
              }
              loadCallback(builder.takeBytes());
            },
            onError: (error) {
              _asyncLoadError(uri.toString(), libraryUri, error);
            });
      })
      .catchError((error) {
        _asyncLoadError(uri.toString(), libraryUri, error);
      });
    // TODO(floitsch): remove this line. It's just here to push an event on the
    // event loop so that we invoke the scheduled microtasks. Also remove the
    // import of dart:async when this line is not needed anymore.
  