anchor.diff:  
     void _checkAvailable() {
       if (_asyncDispatched) {
  -      throw new FileSystemException("An async operation is currently pending", path);
  +      throw new FileSystemException("An async operation is currently pending",
  +                                    path);
       }
       if (closed) {
         throw new FileSystemException("File closed", path);
  
positive.code: class _FileStreamConsumer extends StreamConsumer<List<int>> {
    File _file;
    Future<RandomAccessFile> _openFuture;
    StreamSubscription _subscription;
  
    _FileStreamConsumer(File this._file, FileMode mode) {
      _openFuture = _file.open(mode: mode);
    }
  
    Future<File> addStream(Stream<List<int>> stream) {
      Completer<File> completer = new Completer<File>();
      _openFuture
        .then((openedFile) {
          void error(e, [StackTrace stackTrace]) {
            _subscription.cancel();
            openedFile.close();
  
negative.code:   Future<File> writeAsBytes(List<int> bytes,
                              {FileMode mode: FileMode.WRITE,
                               bool flush: false}) {
      return open(mode: mode).then((file) {
        return file.writeFrom(bytes, 0, bytes.length)
            .then((_) {
              if (flush) return file.flush().then((_) => this);
              return this;
            })
            .whenComplete(file.close);
      });
    }
  
    void writeAsBytesSync(List<int> bytes,
  