Get rid of all the library tags.

test/get/git/check_out_revision_test.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 pub_tests;
-
 import '../../descriptor.dart' as d;
 import '../../test_pub.dart';
 
 main() {
   integration('checks out a package at a specific revision from Git', () {
     ensureGit();
 
     var repo = d.git('foo.git', [
       d.libDir('foo', 'foo 1'),
       d.libPubspec('foo', '1.0.0')
@@ skipping 12 matching lines @@
 
     pubGet();
 
     d.dir(packagesPath, [
       d.dir('foo', [
         d.file('foo.dart', 'main() => "foo 1";')
       ])
     ]).validate();
   });
 }