Add package-root option to the testing scripts

tools/test.dart

Index: tools/test.dart
===================================================================
--- tools/test.dart	(revision 39949)
+++ tools/test.dart	(working copy)
@@ -150,7 +150,9 @@
       // getCrossOriginPortNumber().
       var servers = new TestingServers(new Path(TestUtils.buildDir(conf)),
                                        useContentSecurityPolicy,
-                                       conf['runtime']);
+                                       conf['runtime'],
+                                       null,
+                                       conf['package_root']);
       serverFutures.add(servers.startServers(conf['local_ip'],
           port: conf['test_server_port'],
           crossOriginPort: conf['test_server_cross_origin_port']));