balkian.github.com/font-awesome/less/_rotated-flipped.less

// Rotated & Flipped Icons
// -------------------------

.@{fa-css-prefix}-rotate-90  { .fa-icon-rotate(90deg, 1);  }
.@{fa-css-prefix}-rotate-180 { .fa-icon-rotate(180deg, 2); }
.@{fa-css-prefix}-rotate-270 { .fa-icon-rotate(270deg, 3); }

.@{fa-css-prefix}-flip-horizontal { .fa-icon-flip(-1, 1, 0); }
.@{fa-css-prefix}-flip-vertical   { .fa-icon-flip(1, -1, 2); }
.@{fa-css-prefix}-flip-horizontal.@{fa-css-prefix}-flip-vertical { .fa-icon-flip(-1, -1, 2); }

// Hook for IE8-9
// -------------------------

:root {
  .@{fa-css-prefix}-rotate-90,
  .@{fa-css-prefix}-rotate-180,
  .@{fa-css-prefix}-rotate-270,
  .@{fa-css-prefix}-flip-horizontal,
  .@{fa-css-prefix}-flip-vertical {
    filter: none;
  }
}