When the title is already known use it.
This is similar to the issue fixed in
I714ee391caac9bc56ce4c037967e424b44d9c2fe.
As of this patch all methods within RevisionStore
that call getTitle internally also have an option
to pass in an already known Title object.
Bug: T183548
Change-Id: Ieabca1cf157fb667c75fc907b9da2917f71c61b3
