css/cssom-view/elementFromPoint-dynamic-anon-box.html

<!doctype html>
<meta charset="utf-8">
<title>CSS Test: Hit testing on element previously hidden by an anonymous scroll box</title>
<link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@crisal.io">
<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1433591">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
html, body {
  margin: 0;
  padding: 0;
}
/*
  Create a hidden scrollbox that occupies the whole viewport, then give it
  visibility: hidden dynamically. The link previously under the scrollbox
  should be clickable.
 */
.scrollable {
  position: absolute;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  overflow: scroll;
}

.scrollable .inner {
  display: table-cell;
  width: 100vw;
  height: 100vh;
}
</style>
<div class="scrollable">
  <div class="inner"></div>
</div>
<a href="#">Should be clickable</a>
<script>
test(function() {
  assert_equals(document.elementFromPoint(10, 10).tagName, "DIV",
                "Should hit the scrollbox contents");
  document.querySelector('div').style.visibility = "hidden";
  assert_equals(document.elementFromPoint(10, 10), document.querySelector('a'));
}, "Link should be clickable after hiding a scrollbox with an anonymous table inside");
</script>