code: function cutBezier(bezierArray, t) {
          function __(t) {
              return function(p, q) {
                  return p + t * (q - p);
              };
          }
          var _ = __(t || 0.5),
              ba = bezierArray,
              ax = ba[0],
              ay = ba[1],
              bx = ba[2],
              by = ba[3],
              cx = ba[4],
              cy = ba[5],
              dx = ba[6],
              dy = ba[7],
              ex = _(ax, bx),
              ey = _(ay, by),
              fx = _(bx, cx),
              fy = _(by, cy),
              gx = _(cx, dx),
              gy = _(cy, dy),
              hx = _(ex, fx),
              hy = _(ey, fy),
              jx = _(fx, gx),
              jy = _(fy, gy),
              kx = _(hx, jx),
              ky = _(hy, jy);
          return [
              [ax, ay, ex, ey, hx, hy, kx, ky],
              [kx, ky, jx, jy, gx, gy, dx, dy]
          ];
      }
docs: 将贝塞尔曲线切成两部分
  
  @see http://stackoverflow.com/questions/18655135/divide-bezier-curve-into-two-equal-halves