Fix spinner mixin/variables conversion for Flat UI Pro v1.2.4
Fix spinner mixin/variables conversion for Flat UI Pro v1.2.4

juliomoreira/flat-ui-sass,danhart/flat-ui-sass,juliomoreira/flat-ui-sass,reyesyang/flat-ui-sass,DaRizat/flat-ui-sass,DaRizat/flat-ui-sass,rwu1997/flat-ui-sass,wingrunr21/flat-ui-sass,reyesyang/flat-ui-sass,rwu1997/flat-ui-sass,danhart/flat-ui-sass