code: function makeLink(path) {
              for (var i = 0, l = path.length; i < l; i++) {
                  var cur = path[i];
                  var prev = i === 0 ? path[l - 1] : path[i - 1];
                  var next = i === l - 1 ? path[0] : path[i + 1];
                  cur.index = i;
                  cur.next = next;
                  cur.prev = prev;
              }
  
              return path;
          }
docs: 对path进行双向链表连接
  
  @param  {Array} path 轮廓数组
  @return {Array}         path