Codebase Browser
chromium
Go to App

chromium/content/test/data/accessibility/event/remove-hidden-attribute.html 

<!DOCTYPE html>
<html>
<body>
<div role="list">
  <div role="listitem" aria-label="Item 1"></div>
  <div role="listitem" aria-label="Item 2"></div>
  <div role="listitem" aria-label="Item 3" id="item3" hidden></div>
</div>
<script>
  function go() {
    document.querySelector('#item3').removeAttribute('hidden');
  }
</script>
</body>
</html>