Updated mediawiki/extensions
Project: mediawiki/extensions/MobileFrontend  a7914e6c5ff8f9588ec0e65325d000ac56f712ec

Story 839: Add preview header (follow-up)

I forgot to add that in the original commit implementing the new
preview. Added now to avoid Vibha's wrath.

Change-Id: Icbdfe1fc5bf42e7978db4660d3e4ef4335a22ea3