<!doctype html>
<svg style="position: absolute; width: 0; height: 0">
  <defs>
    <pattern id="rect" width="100" height="100">
      <rect fill="red" width="100" height="100" />
    </pattern>
  </defs>
</svg>
<div id="host"></div>
<script>
  // Should peek the pattern from the shadow root (green), not from the document (red),
  // even though the uri is absolute.
  host.attachShadow({ mode: "open" }).innerHTML = `
    <svg width="100" height="100">
      <defs>
        <pattern id="rect" width="100" height="100">
          <rect fill="lime" width="100" height="100" />
        </pattern>
      </defs>
      <rect fill="url(${location.href}#rect)" width="100" height="100" />
    </svg>
  `;
</script>