fix invalid mixin

Enyo-DCO-1.1-Signed-off-by: Cole Davis <cole.davis@lge.com>
fix to allow use of enyo.super

Enyo-DCO-1.1-Signed-off-by: Cole Davis <cole.davis@lge.com>
Merge pull request #43 from enyojs/fix-flex-mixin

fix invalid mixin

Reviewed-By: Ben Combee (ben.combee@lge.com)