[XHR] Tidy up files for testing XHR's error for mixed content check failure

third_party/WebKit/LayoutTests/http/tests/security/mixedContent/resources/frame-with-insecure-async-xhr-post.html

 <script>
+function report(message) {
+  window.opener.postMessage(message, '*');
+}
+
 var xhr = new XMLHttpRequest();
-xhr.onload = function()
-{
-    window.opener.postMessage('FAIL: XHR succeeded unexpectedly', '*');
-};
-xhr.onerror = function()
-{
-    window.opener.postMessage('DONE', '*');
+xhr.onload = function() {
+  report('FAIL: XHR succeeded unexpectedly');
+}
+xhr.onerror = function() {
+  report('DONE');
 };
 xhr.open("POST", "http://127.0.0.1:8000/xmlhttprequest/resources/access-control-allow-lists.php?origin=*", true);
 xhr.send("foo");
 </script>