menulist-custom-expand-collapse.html

<!DOCTYPE html>
<html>
<head>
<style>
  select { appearance: base-select; }
</style>
</head>
<body>
<select aria-label="Fruit">
  <button>^</button>
  <option>Apple</option>
  <option>Orange</option>
  <option>Banana</option>
</select>
<script>
  var current_pass = 0;
  function go() {
    document.querySelector("button").click()
    return ++ current_pass < go_passes.length;
  }
</script>

</body>
</html>

chromium/content/test/data/accessibility/event/menulist-custom-expand-collapse.html