code: function (point, pred) {
              while (point) {
                  if (pred(point)) {
                      return point;
                  }
  
                  point = prevPoint(point);
              }
  
              return null;
          }
docs: @method prevPointUtil
  
  @param {BoundaryPoint} point
  @param {Function} pred
  @return {BoundaryPoint}