Recreate a collection proxy if the StreamerInfo has enough information.

Since v5.34/10 and v6, we store in StreamerElement of the StreamerInfo
of a class with a CollectionProxy the name of the content type.
It stored in the StreamerElement's title at the beginning in the form:

  <ContentType>

We can now use this information to recreate a proper collection proxy
in the emulated case.
(cherry picked from the v5-34-00-patches branch
 commit 86b327dd)