Add new InternetAddress class with a static lookup function (including IPv6 results).

tests/standalone/io/http_close_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.
 //
 // VMOptions=
 // VMOptions=--short_socket_read
 // VMOptions=--short_socket_write
 // VMOptions=--short_socket_read --short_socket_write
 
 import "package:expect/expect.dart";
@@ skipping 12 matching lines @@
         if (closed == connections) {
           Expect.equals(0, server.connectionsInfo().active);
           Expect.equals(server.connectionsInfo().total,
                         server.connectionsInfo().idle);
           server.close();
         }
       });
     });
     var client = new HttpClient();
     for (int i = 0; i < connections; i++) {
-      client.get("localhost", server.port, "/")
+      client.get("127.0.0.1", server.port, "/")
           .then((request) => request.close())
           .then((response) {
           });
     }
   });
 }
 
 
 void testClientCloseServerListen(int connections) {
   HttpServer.bind().then((server) {
@@ skipping 10 matching lines @@
     server.listen((request) {
       request.listen(
           (_) {},
           onDone: () {
             request.response.close();
             request.response.done.then((_) => check());
           });
     });
     var client = new HttpClient();
     for (int i = 0; i < connections; i++) {
-      client.get("localhost", server.port, "/")
+      client.get("127.0.0.1", server.port, "/")
           .then((request) => request.close())
           .then((response) => check());
     }
   });
 }
 
 
 void testClientCloseSendingResponse(int connections) {
   HttpServer.bind().then((server) {
     int closed = 0;
@@ skipping 13 matching lines @@
       });
       request.response.done
           .catchError((_) {})
           .whenComplete(() {
             check();
             timer.cancel();
           });
     });
     var client = new HttpClient();
     for (int i = 0; i < connections; i++) {
-      client.get("localhost", server.port, "/")
+      client.get("127.0.0.1", server.port, "/")
           .then((request) => request.close())
           .then((response) {
             // Ensure we don't accept the response until we have send the entire
             // request.
             var subscription = response.listen((_) {});
             new Timer(const Duration(milliseconds: 200), () {
               subscription.cancel();
               check();
             });
           });
     }
   });
 }
 
 
 void main() {
   testClientAndServerCloseNoListen(10);
   testClientCloseServerListen(10);
   testClientCloseSendingResponse(10);
 }