Fix SecureSocket tests to look up localhost only once, where possible.

tests/standalone/io/secure_server_client_no_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";
-import "package:path/path.dart";
 
-const HOST_NAME = "localhost";
+InternetAddress HOST;
 const CERTIFICATE = "localhost_cert";
 
 Future testNoClientCertificate() {
   var completer = new Completer();
-  SecureServerSocket.bind(HOST_NAME,
+  SecureServerSocket.bind(HOST,
                           0,
                           CERTIFICATE,
                           requestClientCertificate: true).then((server) {
-    var clientEndFuture = SecureSocket.connect(HOST_NAME,
+    var clientEndFuture = SecureSocket.connect(HOST,
                                                server.port);
     server.listen((serverEnd) {
       X509Certificate certificate = serverEnd.peerCertificate;
       Expect.isNull(certificate);
       clientEndFuture.then((clientEnd) {
         clientEnd.close();
         serverEnd.close();
         server.close();
         completer.complete();
       });
     });
   });
   return completer.future;
 }
 
 Future testNoRequiredClientCertificate() {
   var completer = new Completer();
   bool clientError = false;
-  SecureServerSocket.bind(HOST_NAME,
+  SecureServerSocket.bind(HOST,
                           0,
                           CERTIFICATE,
                           requireClientCertificate: true).then((server) {
-    Future clientDone = SecureSocket.connect(HOST_NAME, server.port)
+    Future clientDone = SecureSocket.connect(HOST, server.port)
       .catchError((e) { clientError = true; });
     server.listen((serverEnd) {
       Expect.fail("Got a unverifiable connection");
     },
     onError: (e) {
       clientDone.then((_) {
         Expect.isTrue(clientError);
         server.close();
         completer.complete();
       });
     });
   });
   return completer.future;
 }
 
 void main() {
   String certificateDatabase = Platform.script.resolve('pkcert').toFilePath();
   SecureSocket.initialize(database: certificateDatabase,
                           password: 'dartdart',
                           useBuiltinRoots: false);
 
   asyncStart();
-  testNoRequiredClientCertificate()
+  InternetAddress.lookup("localhost").then((hosts) => HOST = hosts.first)
+    .then((_) => testNoRequiredClientCertificate())
     .then((_) => testNoClientCertificate())
     .then((_) => asyncEnd());
 }