Get rid of all the library tags.

test/snapshot/doesnt_snapshot_path_dependency_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 '../descriptor.dart' as d;
 import '../test_pub.dart';
 
 main() {
   integration("doesn't create a snapshot for a path dependency", () {
     d.dir("foo", [
       d.libPubspec("foo", "1.2.3"),
       d.dir("bin", [
         d.dir("bin", [d.file("hello.dart", "void main() => print('hello!');")])
       ])
     ]).create();
 
     d.appDir({"foo": {"path": "../foo"}}).create();
 
     pubGet();
 
     d.nothing(p.join(appPath, '.pub', 'bin')).validate();
   });
 }