Suppose you have shadow DOM subtree defined as follows:

<#shadow-root>
    <div id="foo">
        <content select="h1"></content>
    </div>
</#shadow-root>

Then, div#foo hosts another subtree, which goes like this:

<#shadow-root>
    <div>
        <content select="content"></content>
    </div>
</#shadow-root>

In other words, a shadow DOM subtree is hosted inside of a shadow DOM subtree, and the inner tree attempts to redistribute the <content> element. Will this work? How?