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

tests/standalone/io/secure_socket_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
+// OtherResources=certificates/server_chain.p12
+// OtherResources=certificates/server_key.p12
+// OtherResources=certificates/trusted_certs.p12
 
 import "package:async_helper/async_helper.dart";
 import "package:expect/expect.dart";
 import "package:path/path.dart";
 import "dart:async";
 import "dart:io";
 
 String localFile(path) => Platform.script.resolve(path).toFilePath();
 
 SecurityContext serverContext(String certType, String password) =>
@@ skipping 59 matching lines @@
   });
   return completer.future;
 }
 
 main() async {
   asyncStart();
   await test('pem', 'dartdart');
   await test('p12', 'dartdart');
   asyncEnd();
 }