Open commentform and set the height

open_commentform.html

<script>
/* wait for element to be ready */
function tryEl(e) {
  var privEl = document.querySelector('.comment-feed-header')[0];

  if (!privEl) {
    window.requestAnimationFrame(tryEl);
  } else {
    changeAndClick(privEl);
  }
}

function changeAndClick(el) {
  document.getElementById('comment-text').style.height = '40px';

  if (el.children[0].children[0]) {
    el.children[0].children[0].click();
  }
}

tryEl();

</script>