Use "package:" imports for pub.

test/cache/add/package_not_found_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 '../../../lib/src/exit_codes.dart' as exit_codes;
+import 'package:pub/src/exit_codes.dart' as exit_codes;
+
 import '../../test_pub.dart';
 
 main() {
   initConfig();
   integration('fails if the package cound not be found on the source', () {
     serveNoPackages();
 
     schedulePub(args: ["cache", "add", "foo"],
         error: new RegExp(r"Could not find package foo at http://.*"),
         exitCode: exit_codes.UNAVAILABLE);
   });
 }