To be honest I don't get why this lazy registration was done in the
first place. None of the 4 other hooks should ever be called before
the ParserFirstCallInit hook got called.
Also, under which circumstances can the ParserFirstCallInit hook be
called more than once?
Both scenarios would be wrong, as far as I'm concerned. Either I'm
missing something, or this code can indeed be simplified. Maybe it was
something to make it more compatible with older MediaWiki versions?
The only reason I can think of is: in all situations that do not
involve a parser, having the 4 extra hooks registered is pointless.
Does this waste space and/or runtime in the $wgHooks registry?
Change-Id: I5ef1495f4ce7bce940fa5f8e700af3d2c4851a01