Does it work with ShadowDOM?

I'm experiencing troubles with rendering popup inside ShadowDOMed component. It just never renders.

```js
<ShadowDOM>
  <div>
    <style type="text/css">{styles}</style>
    <div>Some text</div>

    <Portal open={true}>
      <h2>FOOO BAR</h2>
    </Portal>
  </div>
</ShadowDOM>
```