Adds SecurityContext.usePrivateKeyBytes

tests/standalone/io/http_proxy_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.
 
 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();
+List<int> readLocalFile(path) => (new File(localFile(path))).readAsBytesSync();
 
 SecurityContext serverContext = new SecurityContext()
   ..useCertificateChain(localFile('certificates/server_chain.pem'))
-  ..usePrivateKey(localFile('certificates/server_key.pem'),
-                  password: 'dartdart');
+  ..usePrivateKeyBytes(readLocalFile('certificates/server_key.pem'),
+                       password: 'dartdart');
 
 SecurityContext clientContext = new SecurityContext()
   ..setTrustedCertificates(file: localFile('certificates/trusted_certs.pem'));
 
 class Server {
   HttpServer server;
   bool secure;
   int proxyHops;
   List<String> directRequestPaths;
   int requestCount = 0;
@@ skipping 441 matching lines @@
   });
   });
 }
 
 main() {
   testInvalidProxy();
   testDirectProxy();
   testProxy();
   testProxyChain();
 }