(Bug 52103) <nowiki/> escape when single quotes wrap new i/b tags

* Updated i/b dom handlers to recognize when the i/b tags
  are preceded/followed by single-quote chars and hence require
  <nowiki/> separation to prevent them being reparsed as
  a different i/b tag than intended.

* The fix in this patchset also covers the scenario fixed in
  git sha 04e52daa3 for bug 50179 and the fix from that patchset
  has been removed.

* Updated html2wt escaping tests for quotes.  In addition, converted
  that test to html2wt mode only since html2html and wt2html causes
  failures because our normalizer cannot strip mw:Placeholder
  metas introduce for <nowiki/>.

* Regenerated selser.changes.json file.  No change in blacklist.

Change-Id: I28f3cffa69be4e11462a68483cf3d3d85d380c85
Merge "(Bug 52103) <nowiki/> escape when single quotes wrap new i/b tags"