Change '127.0.0.1' to 'localhost' to support both IPv4 and IPv6 envs.

test/http_multipart_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:http_server/http_server.dart";
 import "package:mime/mime.dart";
 import "package:unittest/unittest.dart";
 import 'dart:async';
 import 'dart:io';
 import 'dart:convert';
@@ skipping 31 matching lines @@
 
   String toString() {
     return "FormField('$name', '$value', '$contentType', '$filename')";
   }
 }
 
 void postDataTest(List<int> message,
                   String contentType,
                   String boundary,
                   List<FormField> expectedFields,
-                  {defaultEncoding: LATIN1}) {
-  HttpServer.bind("127.0.0.1", 0).then((server) {
+                  {defaultEncoding: LATIN1}) async {
+  var addr = (await InternetAddress.lookup("localhost"))[0];
+  HttpServer.bind(addr, 0).then((server) {
     server.listen((request) {
       String boundary = request.headers.contentType.parameters['boundary'];
       request
           .transform(new MimeMultipartTransformer(boundary))
           .map((part) => HttpMultipartFormData.parse(
               part, defaultEncoding: defaultEncoding))
           .map((multipart) {
             var future;
             if (multipart.isText) {
               future = multipart.join();
@@ skipping 15 matching lines @@
                 });
           })
           .toList()
           .then(Future.wait)
           .then((fields) {
             expect(fields, equals(expectedFields));
             request.response.close().then((_) => server.close());
           });
     });
     var client = new HttpClient();
-    client.post('127.0.0.1', server.port, '/')
+    client.post('localhost', server.port, '/')
         .then((request) {
           request.headers.set('content-type',
                               'multipart/form-data; boundary=$boundary');
           request.add(message);
           return request.close();
         })
         .then((response) {
           client.close();
         });
   });
@@ skipping 148 matching lines @@
                'multipart/form-data',
                '----WebKitFormBoundaryfe0EzV1aNysD1bPh',
                [new FormField('name', 'øv')]);
 }
 
 
 void main() {
   testEmptyPostData();
   testPostData();
 }