Fix viewing older Entity revisions

This is done by constructing an EntityRevision object
with the old revision id instead of just using the current
(latest one) in EntityContent.
After having fixed that, we can use this EntityRevision
object to fetch the correct version of the Entity for
the deferred rendering (EntityViewPlaceholderExpander)
of the "In other languages" box.

Bug: 63309
Change-Id: Id6fbbc85148d5efe6545d5a91a99b5ec19e96665
Merge "Fix viewing older Entity revisions"