Add test directive to include other files used by a test in its compiled output directory.

tests/standalone/io/secure_multiple_client_server_test.dart

 // Copyright (c) 2013, 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.
 //
 // VMOptions=
 // VMOptions=--short_socket_read
 // VMOptions=--short_socket_write
 // VMOptions=--short_socket_read --short_socket_write
+// OtherResources=certificates/server_chain.pem
+// OtherResources=certificates/server_key.pem
+// OtherResources=certificates/trusted_certs.pem
 
 import "dart:async";
 import "dart:io";
 
 import "package:async_helper/async_helper.dart";
 import "package:expect/expect.dart";
 
 InternetAddress HOST;
 SecureServerSocket SERVER;
 
@@ skipping 37 matching lines @@
 
 void main() {
   asyncStart();
   InternetAddress.lookup("localhost").then((hosts) => HOST = hosts.first)
       .then((_) => startServer())
       .then((_) => ['ale', 'bar', 'che', 'den', 'els'].map(testClient))
       .then((futures) => Future.wait(futures))
       .then((_) => SERVER.close())
       .then((_) => asyncEnd());
 }