This fixes incremental layout of nodes that match pseudo-class selectors such
as :first-child, :nth-child, :last-child, :first-of-type, etc.

* Fixes #8191
* Fixes #9063
* Fixes #9303
* Fixes #9448

This code is based on the following flags from Gecko:
https://hg.mozilla.org/mozilla-central/file/e1cf617a1f28/dom/base/nsINode.h#l134