Updated mediawiki/extensions
Project: mediawiki/extensions/MobileFrontend  db40dad55b162e8fa2ec3e2ad6d0fad4f42ef87f

Story 1030: Clean up common.less

Remove undocumented rules, move hacks to hacks.less, scope all
content-related rules inside .content.

Change-Id: Ia00fc80fc01aa84db197b0f7d3e5ed46c3ce8cd0