<!DOCTYPE html>
<style>
.first:empty { color: blue; }
</style>
<script src="util.js"></script>
<script>
window.onload = function() {
  let root = document.createElement("div");
  let first = document.createElement("div");
  first.className = "first";
  first.appendChild(document.createElement("div"));
  root.appendChild(first);
  root.appendChild(build_dom(64000, "div"));
  document.body.appendChild(root);
  flush_layout(root);
  perf_start();
  first.firstChild.remove();
  flush_style(root);
  perf_finish();
};
</script>
