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

tests/standalone/io/secure_server_client_no_certificate_test.dart

Index: tests/standalone/io/secure_server_client_no_certificate_test.dart
diff --git a/tests/standalone/io/secure_server_client_no_certificate_test.dart b/tests/standalone/io/secure_server_client_no_certificate_test.dart
index 3ffeb2253cb9201ccb5e4ac7138df8417c1b284f..888f9888fc26cc6084e58001e2f837472a8478e8 100644
--- a/tests/standalone/io/secure_server_client_no_certificate_test.dart
+++ b/tests/standalone/io/secure_server_client_no_certificate_test.dart
@@ -7,18 +7,17 @@ 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;
@@ -37,11 +36,11 @@ Future testNoClientCertificate() {
 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");
@@ -64,7 +63,8 @@ void main() {
                           useBuiltinRoots: false);
 
   asyncStart();
-  testNoRequiredClientCertificate()
+  InternetAddress.lookup("localhost").then((hosts) => HOST = hosts.first)
+    .then((_) => testNoRequiredClientCertificate())
     .then((_) => testNoClientCertificate())
     .then((_) => asyncEnd());
 }