Get rid of all the library tags.

test/serve/does_not_serve_hidden_assets_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS d.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';
 import 'utils.dart';
 
 main() {
   integration("doesn't serve hidden assets", () {
     d.dir(appPath, [
       d.appPubspec(),
       d.dir("web", [
         d.file(".outer.txt", "outer contents"),
         d.dir(".dir", [
           d.file("inner.txt", "inner contents"),
         ])
       ])
     ]).create();
 
     pubGet();
     pubServe();
     requestShould404(".outer.txt");
     requestShould404(".dir/inner.txt");
     endPubServe();
   });
 }