d=b0>b0</button>

<div id=p1 popover=auto>
  <button id=b1>b1</button>

  <div id=p2 popover=auto>p2</div>
</div>

<script>
promise_test(async () => {
  const p1 = document.getElementById('p1');
  const p2 = document.getElementById('p2');
  await test_driver.click(b0);
  p1.showPopover();
  await test_driver.click(b1);
  p2.showPopover();

  assert_true(p1.matches(':popover-open'), 'p1 should be open.');
  assert_true(p2.matches(':popover-open'), 'p2 should be open.');

  p2.remove()

  assert_false(p2.matc