Get rid of all the library tags.

lib/src/frontend/expect.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.
 
-library test.frontend.expect;
-
 import 'package:matcher/matcher.dart';
 
 import '../backend/closed_exception.dart';
 import '../backend/invoker.dart';
 
 /// An exception thrown when a test assertion fails.
 class TestFailure {
   final String message;
 
   TestFailure(this.message);
@@ skipping 54 matching lines @@
 
   var mismatchDescription = new StringDescription();
   matcher.describeMismatch(actual, mismatchDescription, matchState, verbose);
 
   if (mismatchDescription.length > 0) {
     description.add('   Which: ${mismatchDescription}\n');
   }
   if (reason != null) description.add(reason).add('\n');
   return description.toString();
 }