window.performance.timing.navigationStart有bug

### Version
1.12.36

### Reproduction link
[https://aq.huya.com/m/third_bind/third_bind.html](https://aq.huya.com/m/third_bind/third_bind.html)

### Steps to reproduce
发现你们的库里面用到window.performance.timing.navigationStart这个方法，在sentry的监控下，发现在IOS报null is not an object (evaluating 'window.performance.timing.navigationStart')

### What is expected?
未知

### What is actually happening?
未知

### Dependencies Version
vue: 2.6.11
better-scroll: 1.15.0