[Bug Report] Width Rendering of el-table Components under IE11

### Element UI version
2.10.0

### OS/Browsers version
IE11

### Vue version
2.6.10

### Reproduction Link
https://codepen.io/WQone/pen/XLEOxY?editors=1111

### Steps to reproduce
在IE11下打开官网表格组件示例 即可复现
Open official website in IE11 browser

（发现IE11可能无法打开codepen链接 ，请直接查看官网https://element.eleme.cn/#/zh-CN/component/table）

### What is Expected?
希望组件在IE中渲染正确的宽度
Hopefully this component will have the right width to render the table

### What is actually happening?
希望组件在IE中渲染正确的宽度
There is no correct rendering of the width it should have