core.html.normalize
#item input.html
<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
</head>
<body>

no parent

<p>paragraph</p>

<hgroup>
  <p>hgroup, paragraph</p>
</hgroup>

<hgroup>
  <hgroup>
    <p>hgroup, hgroup, paragraph</p>
  </hgroup>
</hgroup>

<hgroup>hgroup</hgroup>

<hgroup>
  <hgroup>hgroup, hgroup</hgroup>
</hgroup>

</body>
</html>
#item expected
<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8"/>
  </head>
  <body>
    <p>
      <span>no parent</span>
    </p>
    <p>
      <span>paragraph</span>
    </p>
    <p>
      <span>hgroup, paragraph</span>
    </p>
    <p>
      <span>hgroup, hgroup, paragraph</span>
    </p>
    <p>
      <span>hgroup</span>
    </p>
    <p>
      <span>hgroup, hgroup</span>
    </p>
  </body>
</html>