Fix tests for VM in checked mode.

tests/standalone/io/https_client_certificate_test.dart

 // Copyright (c) 2012, 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 "dart:uri";
 import "dart:isolate";
 
 const SERVER_ADDRESS = "127.0.0.1";
@@ skipping 71 matching lines @@
       new Path.fromNative(new Options().script).directoryPath.append('pkcert/');
   SecureSocket.initialize(database: testPkcertDatabase.toNativePath(),
                           password: 'dartdart');
 }
 
 void main() {
   var keepAlive = new ReceivePort();
   InitializeSSL();
   // Test two connections in sequence.
   test({'certificateName': null})()
-      .then(test({'certificateName': 'localhost_cert'}))
+      .then((_) => test({'certificateName': 'localhost_cert'})())
       .then((_) {
     Expect.equals(2, numClientCertificatesReceived);
     keepAlive.close();
   });
 }