Get rid of all the library tags.

lib/src/util/forkable_stream.dart

 // Copyright (c) 2015, 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.
 
 // TODO(nweiz): Get rid of this when https://codereview.chromium.org/1241723003/
 // lands.
-library test.util.forkable_stream;
-
 import 'dart:async';
 
 import 'package:async/async.dart' hide ForkableStream;
 
 /// A single-subscription stream from which other streams may be forked off at
 /// the current position.
 ///
 /// This adds an operation, [fork], which produces a new stream that
 /// independently emits the same events as this stream. Unlike the branches
 /// produced by [StreamSplitter], a fork only emits events that arrive *after*
@@ skipping 140 matching lines @@
 
     // Don't iterate directly over the set because [controller.close] might
     // cause it to be modified synchronously.
     for (var controller in _controllers.toList()) {
       controller.close();
     }
     _controllers.clear();
   }
 }