discourse/app/assets/stylesheets/vendor/font_awesome/_mixins.scss

// Mixins
// --------------------------

@mixin fa-icon-rotate($degrees, $rotation) {
    transform: rotate($degrees);
    -webkit-transform: rotate($degrees);
}

@mixin fa-icon-flip($horiz, $vert, $rotation) {
    transform: scale($horiz, $vert);
    -webkit-transform: scale($horiz, $vert);
}