Show changed bits on file version (oldimage) revdel logs.

Don't know if there is a bug for this or not, but I noticed that we don't get "content hidden/unhidden" type notes for revdel logs when they're for file revisions (instead of page revisions)

Change-Id: I0de389e601aaad7fd8abb989b4a0004082206894
Merge "Show changed bits on file version (oldimage) revdel logs."