Get rid of all the library tags.

lib/src/hmac.dart

 // Copyright (c) 2012, 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 crypto.hmac;
-
 import 'dart:convert';
 import 'dart:typed_data';
 
 import 'package:typed_data/typed_data.dart';
 
 import 'digest.dart';
 import 'digest_sink.dart';
 import 'hash.dart';
 
 /// An implementation of [keyed-hash method authentication codes][rfc].
@@ skipping 157 matching lines @@
 
   void close() {
     if (_isClosed) return;
     _isClosed = true;
 
     _innerSink.close();
     _outerSink.add(_innerResultSink.value.bytes);
     _outerSink.close();
   }
 }