shadow-dom/slot-fallback-content-008.html

<!DOCTYPE html>
<meta charset="utf-8" >
<meta name="author" title="Di Zhang" href="mailto:dizhangg@chromium.org">
<meta name="assert" content="Complex slot fallback content, when dynamically created">
<title>Shadow DOM: Slots and fallback contents</title>
<link rel="match" href="slot-fallback-content-008-ref.html">

<div id="host">FAIL
  <div id="host2">FAIL
    <div id="A">A
        <slot id="slot1" name="slot1">FAIL</slot>
    </div>
    <div id="B">B
      <slot id="slot2" name="slot2">SLOT2
        <slot id="slot3" name="slot3">SLOT3</slot>
      </slot>
    </div>
    <slot id="slot4" name="slot4" slot="slot1">FAIL</slot>
    <slot id="slot5" name="slot5" slot="slot3">SLOT5
      <div id="C">C</div>
    </slot>
  </div>
  <div id="D" slot="slot4">D</div>
</div>

<script>
const shadowRoot2 = host2.attachShadow({ mode: "open" });
shadowRoot2.appendChild(A);
shadowRoot2.appendChild(B);

const shadowRoot = host.attachShadow({ mode: "open" });
shadowRoot.appendChild(host2);

</script>