<!DOCTYPE html>
<html>
<head>
<style>
body {
  margin: 0;
}

.animated {
  -webkit-animation: test 1s;
}

@-webkit-keyframes test {
  from {
    padding: 0;
  }
  to {
    padding: 0;
  }
}
</style>
</head>
<body>
<ul><li>Test</li></ul>
</body>
<script>
if (window.testRunner)
  testRunner.dumpAsText();

if (window.internals) {
  document.body.offsetHeight;
  let layoutCountBefore = internals.layoutCount;
  // This should not trigger layout.
  document.body.classList.add('animated');
  document.body.offsetHeight;
  let layoutCountAfter = internals.layoutCount;

  let pre = document.createElement('pre');
  document.body.appendChild(pre);
  pre.innerHTML = "Number of layouts triggered: " + (layoutCountAfter - layoutCountBefore);
}
</script>
</html>