Get rid of all the library tags.

test/upgrade/hosted/upgrade_removed_constraints_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("upgrades dependencies whose constraints have been removed", () {
     servePackages((builder) {
       builder.serve("foo", "1.0.0", deps: {"shared_dep": "any"});
       builder.serve("bar", "1.0.0", deps: {"shared_dep": "<2.0.0"});
       builder.serve("shared_dep", "1.0.0");
       builder.serve("shared_dep", "2.0.0");
@@ skipping 13 matching lines @@
 
     pubUpgrade();
 
     d.packagesDir({
       "foo": "1.0.0",
       "bar": null,
       "shared_dep": "2.0.0"
     }).validate();
   });
 }