Fix hostname lookup on Windows

tests/standalone/src/io/HttpClientTest.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:io");
+
+void testGoogle() {
+  HttpClient client = new HttpClient();
+  var conn = client.get('www.google.com', 80, '/');
+
+  conn.onRequest = (HttpClientRequest request) {
+    request.keepAlive = false;
+    request.outputStream.close();
+  };
+  conn.onResponse = (HttpClientResponse response) {
+    Expect.isTrue(response.statusCode < 500);
+    response.inputStream.onClosed = () {
+      response.inputStream.read();
+    };
+    response.inputStream.onClosed = () {
+      client.shutdown();
+    };
+  };
+}
+
+void main() {
+  testGoogle();
+}