ent.createElement("span");
  nonConstructedSpan.classList.add(".nonConstructedSpan");
  divNonConstructed.appendChild(nonConstructedSpan);

  assert_equals(getComputedStyle(iframeDiv).color, "rgb(0, 0, 0)");
  assert_throws_dom('NotAllowedError', () => { document.adoptedStyleSheets = [iframeStyleSheet]; });
  assert_equals(getComputedStyle(iframeDiv).color, "rgb(0, 0, 0)");
}, 'Adding non-constructed stylesheet to AdoptedStyleSheets is not allowed when the owner document of the stylesheet and the AdoptedSty