function substractTRBL(trblA, trblB) {
  return {
    top: trblA.top - trblB.top,
    right: trblA.right - trblB.right,
    bottom: trblA.bottom - trblB.bottom,
    left: trblA.left - trblB.left
  };
}
Substract a TRBL from another

@param {RectTRBL} trblA
@param {RectTRBL} trblB

@return {RectTRBL}