An BlockContainer inside an InlineNode is called from the
`for each in inclusive_subtree_of_type` but is also a fragment
of that InlineNode. Don't count the the Node twice.
Inline nodes in our layout tree have a position, so let's show it. By
centralizing the logic for this, block nodes now lose their redundant
'content-size' dump info which is already part of the box model dump.
All fragments inside an atomic inline box should stay within that box,
otherwise we'll screw up the paint order and paint them behind things
that they're supposed to be on top of.
This fixes an issue with inline-block content not appearing on sites
like Google Docs and Reddit, among others.
