Updated mediawiki/extensions
Project: mediawiki/extensions/MobileFrontend  205a3d50c01107a3f19050da831c03de1f7f483c

Require MW_INSTALL_PATH in both makefile and gruntfile

If the variable is not set, then it will bailout loudly with an error message
with examples.

Bug: T85125
Change-Id: I8917ddbb93afbbf48228140ec279ed6f45c98459