Unflake fast/loader/resources/unload-hyperlink-targeted-subframe.html

LayoutTests/fast/loader/resources/unload-hyperlink-targeted-subframe.html

 <script>
 addEventListener("unload", function() {
   var anc = document.getElementById("lk");
   var evt = document.createEvent("MouseEvents");
   evt.initMouseEvent(
       "click", true, true, window, 1, 0, 0, 0, 0,
       false, false, false, false, 0, anc);
   anc.dispatchEvent(evt);
 }, false);
 </script>
 <a id="lk" target="_top"
    href="pass-and-notify-done.html">Link to iframe.</a>
 <script>
+window.onload = function() {
 window.location = "about:blank";
+}
 </script>