Get rid of all the library tags.

test/serve/supports_user_defined_declaring_transformers_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS d.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 pub_tests;
-
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 import 'utils.dart';
 
 const DECLARING_TRANSFORMER = """
 import 'dart:async';
 
 import 'package:barback/barback.dart';
 
 class DeclaringRewriteTransformer extends Transformer
@@ skipping 46 matching lines @@
 
     requestShouldSucceed("foo.final", "foo.out.final");
     server.stdout.expect(emitsLines(
         '[Info from LazyRewrite]:\n'
         'Rewriting myapp|web/foo.txt.\n'
         '[Info from DeclaringRewrite]:\n'
         'Rewriting myapp|web/foo.out.'));
     endPubServe();
   });
 }