[Bug Report] a change in the value of the tooltip disabled property causes the browser to scroll

### Element UI version
2.4.5

### OS/Browsers version
macOS 10.13.6/ chorme 77.0.3865.120

### Vue version
2.6.10

### Reproduction Link
https://codepen.io/xiaodou-icst/pen/yLepNRb

### Steps to reproduce
1、点击【点击开启tooltip功能】按钮。
2、点击【点击关闭tooltip功能】按钮。
重复上述1、2操作

### What is Expected?
浏览器不出现滚动条，按钮及页面不闪动

### What is actually happening?
浏览器出现滚动条