function getResizeDirections(oldBounds, newBounds) {
  var directions = '';

  oldBounds = asTRBL(oldBounds);
  newBounds = asTRBL(newBounds);

  if (oldBounds.top > newBounds.top) {
    directions = directions.concat('n');
  }

  if (oldBounds.right < newBounds.right) {
    directions = directions.concat('w');
  }

  if (oldBounds.bottom < newBounds.bottom) {
    directions = directions.concat('s');
  }

  if (oldBounds.left > newBounds.left) {
    directions = directions.concat('e');
  }

  return directions;
}
Get directions of resize as {n|w|s|e} e.g. "nw".

@param {Rect} oldBounds
@param {Rect} newBounds

@return {Direction} Resize directions as {n|w|s|e}.