= document.getElementById("target");
const contents = document.getElementById("contents");

function checkSize(expectedWidth, expectedHeight, msg) {
  assert_equals(target.clientWidth, expectedWidth, msg + " - clientWidth");
  assert_equals(target.clientHeight, expectedHeight, msg + " - clientHeight");
}

function nextRendering() {
  return new Promise(resolve => {
    requestAnimationFrame(() => requestAnimationFrame(() => resolve()));
  });
}

function cleanup() {
  parent.className = "";
  target.classNa