Open
Description
Describe
页面渲染的时候scrollToIndex到指定位置，然后滚轮上滑会出现一段空白
To Reproduce
Steps to reproduce the behavior:
1.页面加载完成后，滚轮向上滚动
Reproduce demo
https://codesandbox.io/s/live-demo-virtual-list-e1ww1 ](https://codesandbox.io/s/live-demo-virtual-list-forked-vvi73?file=/src/App.vue)
Other
- Version [e.g. 2.2.9]
- Browser [e.g. chrome, safari]