Add unique serial numbers to sample X509 certificates. Remove the "sendClientCertificate" parameter…

tests/standalone/io/secure_server_client_certificate_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 "dart:async";
 import "dart:io";
 
 import "package:async_helper/async_helper.dart";
 import "package:expect/expect.dart";
 
@@ skipping 14 matching lines @@
   ..usePrivateKey(localFile('certificates/client1_key.pem'),
       password: 'dartdart');
 
 SecurityContext clientNoCertContext = new SecurityContext()
   ..setTrustedCertificates(file: localFile('certificates/trusted_certs.pem'));
 
 Future testClientCertificate({bool required, bool sendCert}) async {
   var server = await SecureServerSocket.bind(HOST, 0, serverContext,
       requestClientCertificate: true, requireClientCertificate: required);
   var clientContext = sendCert ? clientCertContext : clientNoCertContext;
-  var clientEndFuture = SecureSocket.connect(HOST, server.port,
-      context: clientContext, sendClientCertificate: true);
+  var clientEndFuture =
+      SecureSocket.connect(HOST, server.port, context: clientContext);
   if (required && !sendCert) {
     try {
       await server.first;
     } catch (e) {
       try {
         await clientEndFuture;
       } catch (e) {
         return;
       }
     }
@@ skipping 20 matching lines @@
 
 main() async {
   asyncStart();
   HOST = (await InternetAddress.lookup("localhost")).first;
   await testClientCertificate(required: false, sendCert: true);
   await testClientCertificate(required: true, sendCert: true);
   await testClientCertificate(required: false, sendCert: false);
   await testClientCertificate(required: true, sendCert: false);
   asyncEnd();
 }