layout/reftests/css-display/display-contents-dyn-insert-text.html

<!doctype html>
<meta charset="utf-8">
<link rel="author" title="Markus Stange" href="mailto:mstange@themasta.com">
<link rel="help" href="https://drafts.csswg.org/css-display/#box-generation">
<title>Bug 1338678 - display:contents makes textContent disappear</title>
<div style="display: contents">
  <div id="element"></div>
</div>
<script>
window.onload = function() {
  document.body.offsetTop;
  var element = document.getElementById('element');
  element.textContent = "FAIL";
  element.textContent = "PASS";
}
</script>