Add HTML test with two dart scripts on one page.

tests/html/two_scripts_test_second.dart

 // Copyright (c) 2014, 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.
 
-library http.test.html_utils;
-
+library TwoScriptsTestSecond;
 import 'dart:html';
 
-export '../utils.dart';
+aGlobalFunction() {
+  window.postMessage('second_global', '*');
+}
 
-/// The test server's echo URL.
-Uri get echoUrl => Uri.parse(
-    '${window.location.protocol}//${window.location.host}/echo');
+main() {
+  window.postMessage('second_local', '*');
+  aGlobalFunction();
+}