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

tests/standalone/io/http_proxy_advanced_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.
 
+// OtherResources=certificates/server_chain.pem
+// OtherResources=certificates/server_key.pem
+// OtherResources=certificates/trusted_certs.pem
+
 import "package:convert/convert.dart";
 import "package:crypto/crypto.dart";
 import "package:expect/expect.dart";
 import "package:path/path.dart";
 import "dart:async";
 import "dart:io";
 import 'dart:convert';
 
 String localFile(path) => Platform.script.resolve(path).toFilePath();
 
@@ skipping 610 matching lines @@
   // The two invocations use the same global variable for state -
   // run one after the other.
   testProxyAuthenticate(false)
       .then((_) => testProxyAuthenticate(true));
 
   // This test is not normally run. It can be used for locally testing
   // with a real proxy server (e.g. Apache).
   // testRealProxy();
   // testRealProxyAuth();
 }