Font-Awesome/assets/font-awesome/less/mixins.less

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

.fa-icon-rotate(@degrees, @rotation) {
  filter: progid:DXImageTransform.Microsoft.BasicImage(rotation=@rotation);
  -webkit-transform: rotate(@degrees);
     -moz-transform: rotate(@degrees);
      -ms-transform: rotate(@degrees);
       -o-transform: rotate(@degrees);
          transform: rotate(@degrees);
}

.fa-icon-flip(@horiz, @vert, @rotation) {
  filter: progid:DXImageTransform.Microsoft.BasicImage(rotation=@rotation, mirror=1);
  -webkit-transform: scale(@horiz, @vert);
     -moz-transform: scale(@horiz, @vert);
      -ms-transform: scale(@horiz, @vert);
       -o-transform: scale(@horiz, @vert);
          transform: scale(@horiz, @vert);
}