Fully utilize LinkTarget passed to getRevisionByTitle
Failure of getRevisionByTitle to pass its LinkTarget argument
to newRevisionFromRow resulted in a needless second instantiation
of the Title (an extra query).
Because newRevisionFromRow needs a Title, not just a LinkTarget,
it is unfortunately necessary to call Title::newFromLinkTarget
on it for now -- however this does not involve a DB lookup and
is on track to be fixed with revisions to the Title class.