Get rid of all the library tags.

test/snapshot/doesnt_resnapshot_when_a_dependency_is_unchanged_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("doesn't recreate a snapshot when no dependencies of a package "
       "have changed", () {
     servePackages((builder) {
       builder.serve("foo", "1.2.3", deps: {"bar": "any"}, contents: [
         d.dir("bin", [d.file("hello.dart", "void main() => print('hello!');")])
       ]);
       builder.serve("bar", "1.2.3");
     });
 
     d.appDir({"foo": "1.2.3"}).create();
 
     pubGet(output: contains("Precompiled foo:hello."));
 
     pubUpgrade(output: isNot(contains("Precompiled foo:hello.")));
 
     d.dir(p.join(appPath, '.pub', 'bin'), [
       d.file('sdk-version', '0.1.2+3\n'),
       d.dir('foo', [d.matcherFile('hello.dart.snapshot', contains('hello!'))])
     ]).validate();
   });
 }