Bug 68395: Tweaks to p-wrapping around formatting tags

* Formatting tags that wrap block content are legit. in HTML5,
  but the paragraph-wrapper was effectively splitting the
  opening and closing formatting tags into separate p wrappers
  which changed the formatting quite a bit (see bugs 66749 and 63642
  which are symptoms of this behavior).

* This patch handles a special case where the formatting tag is a
  tight wrap around a block tag without any additional content between
  the formatting and block tag. This fixes some issues as with the
  changes to parser tests.

  Ex: "<small>\n*a\n</small>" or "<b><div>foo</div></b>"

* More tests green.

* This patch still does p-wrapping around formatting tags if they
  contain content -- and it seems like the right thing to do so far
  based on looking at tests on en.wp.

  More thorough investigation to follow after rt-testing.

Change-Id: I6f3050f5c6bebe9f90f7309350ad5fbad07a18a1
Merge "Bug 68395: Tweaks to p-wrapping around formatting tags"