Temporarily tweak <nowiki/> removal heuristic a bit

* Looks like there are a lot of wikitext scenarios like this in
  roundtrip testing.

'<nowiki/>''foo'' and ''[[bar]]''

  The existing conservative heuristic won't strip the nowiki in this
  scenario. So, I've added another hacky heuristic for now.

  We really need a line-based heuristic that can examine wikitext chunks
  and their types (text, quote, link, etc.) so as to better determine
  what kinds of escaping is necessary.

  That is coming later as part of what Scott is working on.

  For now, this should help us minimize regressions.

Change-Id: I2759e76d56703254d3907ac447644457bc007b4b
Bug fix in list wikitext escape handler

* If the parent node of the text node is not a list-node,
  there is no need to worry about escaping!

* Updated existing parser test to capture this.

Change-Id: Iebfd43c85082b4c506d5fb770f1a035b35e3802c