<!DOCTYPE html>
<html class="reftest-wait">
  <!-- Test: if input is no longer readonly, it is candidate for constraint
             validation and should be affected by :invalid pseudo-class. -->
  <link rel='stylesheet' type='text/css' href='style.css'>
  <body onload="document.getElementById('i').removeAttribute('readonly'); document.documentElement.className='';">
    <input class='invalid' id='i' readonly required>
  </body>
</html>