Steps组件，在ie9下存在样式错乱问题

[gyh9457]

• I have searched the issues of this repository and believe that this is not a duplicate.

Reproduction link

https://ant.design/components/steps-cn/

Steps to reproduce

demo上即可重现

What is expected?

样式正常

What is actually happening?

步骤之间的线条样式错乱

Environment	Info
antd	3.11.6
React	16.7.6
System	win7
Browser	ie9

[orzyyyy]

ie9 没报错，内存占得很多，Icon 旋转动画消失

看上去是 .ant-steps-item 的 overflow 没用了

[gyh9457]

动画问题是所有组件都存在的，我这里想说的是线条超出的样式问题。