IndexOf('.') + 1); // e.g. "test"
      var REMOTE_HOST = host_info.REMOTE_HOST;
      var iframe = document.getElementById("iframe");
      var iframe_url = new URL("support/document_domain_setter_iframe.html", document.location);
      iframe_url.hostname = REMOTE_HOST;
      iframe.src = iframe_url;

      test(function() {
        assert_throws_dom("SecurityError", function() { document.domain = SUFFIX_HOST; });
        assert_throws_dom("SecurityError", function() { document.domain = "." + SUFFIX_HOST;