Modernize the package's style.

lib/src/stream_sink_transformer/stream_transformer_wrapper.dart

 // Copyright (c) 2016, 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.
 
-library async.stream_sink_transformer.stream_transformer_wrapper;
-
 import 'dart:async';
 
 import '../stream_sink_transformer.dart';
 
 /// A [StreamSinkTransformer] that wraps a pre-existing [StreamTransformer].
 class StreamTransformerWrapper<S, T> implements StreamSinkTransformer<S, T> {
   /// The wrapped transformer.
   final StreamTransformer<S, T> _transformer;
 
   const StreamTransformerWrapper(this._transformer);
@@ skipping 36 matching lines @@
     _controller.addError(error, stackTrace);
   }
 
   Future addStream(Stream<S> stream) => _controller.addStream(stream);
 
   Future close() {
     _controller.close();
     return _inner.done;
   }
 }