adowDiv = attachShadowDiv(span);
  const sheet = new CSSStyleSheet();
  span.shadowRoot.adoptedStyleSheets = [sheet];

  const iframe = document.createElement("iframe");
  document.body.appendChild(iframe);
  const newSpan = iframe.contentDocument.importNode(span, true);
  iframe.contentDocument.body.appendChild(newSpan);
  assert_equals(newSpan.shadowRoot, null);
}, 'Importing a shadow host will not copy shadow root, and also adoptedStyleSheets');

test(() => {
  const span = document.createElement("span")