fix(ticks): tickMethods for tiny numbers

[pearmini]

修复了下面出现死循环的问题：

extended(9.899999999999999, 9.9)
pretty(9.899999999999999, 9.9)

出现原因是精度问题：

const start = 9.899999999999999;
const end = 9.9;
const step = 5e-15;
for(let i = start; i < end; i += step) {} // 死循环 i += step 始终等于 9.899999999999999

const start = 19799999999999996;
const end = 19799999999999996;
const step = 1;
for(let i = start; i <= end; i += step) {} // 死循环 i += step 始终等于 19799999999999996

解决办法

const start = 9.899999999999999;
const end = 9.9;
const step = 5e-15;
const count = Math.floor((start - end) / step);
for(let i = 0; i < count; i += 1) {}