CON 1888 - Media support on Venus

Support for 

* Galleries
* Slideshow
* Slider
* New galleries
* Videos

File: mediawiki.basic.legacy.css is part of /skins/common/shared.css
I can't find usage of clearfix in MediaGallery.scss 
Can you point me where should I look?
BTW if it's required by other file why we don't import it there?