Use "package:" imports for pub.

test/serve/native_watch_removed_file_test.dart

 // Copyright (c) 2013, 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 'package:path/path.dart' as path;
+import 'package:pub/src/io.dart';
 import 'package:scheduled_test/scheduled_test.dart';
 
-import '../../lib/src/io.dart';
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 import 'utils.dart';
 
 // TODO(nweiz): Default to testing the native watcher and add an explicit test
 // for the polling watcher when issue 14941 is fixed.
 
 main() {
   initConfig();
   integration("stop serving a file that is removed when using the native "
       "watcher", () {
     d.dir(appPath, [
       d.appPubspec(),
       d.dir("web", [
         d.file("index.html", "body")
       ])
     ]).create();
 
     pubServe(args: ["--no-force-poll"]);
     requestShouldSucceed("index.html", "body");
 
     schedule(() => deleteEntry(
         path.join(sandboxDir, appPath, "web", "index.html")));
 
     waitForBuildSuccess();
     requestShould404("index.html");
     endPubServe();
   });
 }