Get rid of all the library tags.

test/snapshot/prints_errors_for_broken_snapshots_test.dart

 // Copyright (c) 2014, 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 pub_tests;
-
 import 'package:path/path.dart' as p;
 import 'package:scheduled_test/scheduled_test.dart';
 
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 
 main() {
   integration("prints errors for broken snapshot compilation", () {
     servePackages((builder) {
       builder.serve("foo", "1.2.3", contents: [
@@ skipping 27 matching lines @@
         d.nothing('hello.dart.snapshot'),
         d.nothing('goodbye.dart.snapshot')
       ]),
       d.dir('bar', [
         d.nothing('hello.dart.snapshot'),
         d.nothing('goodbye.dart.snapshot')
       ])
     ]).validate();
   });
 }