https://developer.mozilla.org/en-US/docs/Web/API/PerformanceTiming
https://www.w3.org/TR/navigation-timing/?spm=a2c63.p38356.879954.7.161114c8FvWjxj
navigation timing中各时间节点的意义
原文：https://www.cnblogs.com/eret9616/p/15196149.html
