ost.focus();
  assert_equals(shadowRoot.activeElement, aboveSlots);
  assert_equals(document.activeElement, host);
}, "focus() on host with delegatesFocus & tabindex = 0, all other tabindex=-1");

test(() => {
  resetTabIndexAndFocus();
  removeAllTabIndex();
  // No focusable element under #host in the flat tree.
  host.focus();
  assert_equals(shadowRoot.activeElement, null);
  assert_equals(document.activeElement, document.body);
}, "focus() on host with delegatesFocus, all without tabindex");

test(() =