Estée Lauder's fresh new face, Kendall Jenner, has dropped her very first product for the major beauty brand, a mascara primer. Initial reaction: I want it. Second reaction: um, I definitely don't have a Little Black Primer in my makeup bag ATM, so what exactly does it do, please? We've got a feeling these Qs are universal, so we've done some digging — here are three ways you can use this Jenner-recommended product...