chromium/third_party/blink/web_tests/fast/dynamic/window-resize-scrollbars-test.html

<!DOCTYPE html>
<script>
  if (window.testRunner)
    testRunner.waitUntilDone();

  window.onload = async function() {
    var width = innerWidth;
    var height = innerHeight;

    document.documentElement.style.height = height - 32 + "px";
    document.documentElement.style.width = width - 32 + "px";
    document.body.offsetTop;

    var resizePromise = new Promise(resolve => window.onresize = resolve);
    resizeTo(outerWidth - 24, outerHeight - 24);
    await resizePromise;

    if (window.testRunner)
      testRunner.notifyDone();
  };

</script>
<body style="background: green">
</body>