Improvement to dom pass that migrates trailing newlines.

* Trailing newlines should be migrated out of DOM nodes that either:
  - ends a line in wikitext (td, ol, li, etc.) OR
  - it is the last node in the DOM subtree rooted at a node that
    ends a line in wikitext.
	Ex: <td><small><small>foo\n</small></small></td>

* Also effectively reverts the change from d41c6ffc since tbody
  doesn't have a wikitext equivalent.  The improved migration above
  should probably take care of whatever serialization scenario
  prompted us to add it in.

* One more wt2html test now green when tbody was removed from the
  list of nodes that ends a line in WT.  No changes otherwise.

* Eliminates all semantic RT errors on several pages:
  - en:Crosby, Pevar & Raymond
  - en:Liga Heren
  - en:Opinions of the Supreme Court of Canada by Chief Justice McLachlin

Change-Id: Ie563f09087e87eabc3bfc250202a5f432631ef58