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

tests/standalone/io/secure_socket_alpn_test.dart

 // Copyright (c) 2015, 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.
+//
+// OtherResources=certificates/server_chain.pem
+// OtherResources=certificates/server_key.pem
+// OtherResources=certificates/trusted_certs.pem
 
 import 'dart:io';
 import 'dart:convert';
 
 import 'package:expect/expect.dart';
 import 'package:async_helper/async_helper.dart';
 
 const String NAME_LENGTH_ERROR =
     'Length of protocol must be between 1 and 255';
 
@@ skipping 184 matching lines @@
   // Issue  https://github.com/dart-lang/sdk/issues/23580
   // Chromium issue https://code.google.com/p/chromium/issues/detail?id=497770
   testSuccessfulAlpnNegotiationConnection(['a'], ['b'], null);
 
   // Test too short / too long protocol names.
   testInvalidArgument([longname256], NAME_LENGTH_ERROR);
   testInvalidArgument([strangelongname256], NAME_LENGTH_ERROR);
   testInvalidArgument([''], NAME_LENGTH_ERROR);
   testInvalidArgument(tooManyProtocols, MESSAGE_LENGTH_ERROR);
 }