When viewing the page history in Special:Undelete, it is hard to tell what
changes were made, especially if a single revision was deleted, and and we would
want to see the change made since it was the reason it was deleted. Deleted
revisions listed in Special:Undelete should be viewable as diffs and not just
revisions. They should show the changes between two revisions in sequence, even
if one revision is not deleted and the other is, just like normal diffs.