chromium/content/test/data/accessibility/html/img-link-empty-alt-set.html

<!DOCTYPE html>
<!--
  @WAIT-FOR:done
-->
<body>
  <a href="/">
    <img src="pipe.jpg" id="img" alt="">
  </a>
  
  <script async defer>
      document.addEventListener('DOMContentLoaded', () => {
        requestAnimationFrame(() => {
          requestAnimationFrame(async () => {
            await new Promise(resolve => setTimeout(resolve, 1000));
            document.getElementById('img').setAttribute('alt','test');
            document.title = 'done';
        });
      })
    });
  </script>
</body>