The [Bug Report] tabs page signature cannot be rolled properly.

[LemonAppleMo]

Element UI version

2.4.7

OS/Browsers version

windows 10/ chrome 版本 69.0.3497.81（正式版本） （64 位）

Vue version

2.5.17

Reproduction Link

https://jsfiddle.net/yjofe873/

Steps to reproduce

一直点击add tab 按钮 等到出现左右滚动按钮， 点击回到第二个页签， 但是无法回到第二个页签

What is Expected?

可以滚动到第二个页签的位置

What is actually happening?

不可以滚动到第二个页签的位置

[element-bot]

Translation of this issue:

Element UI version
2.4.7

OS/Browsers version
Windows 10/ chrome version 69.0.3497.81 (official version) (64 bits)

Vue version
2.5.17

Reproduction Link
https://jsfiddle.net/yjofe873/

Steps to reproduce
Click the add tab button until the left and right scroll button appears and click back to the second tab, but you can't go back to the second tab

What is Expected?
You can scroll to the second page tab.

What is actually happening?
You can not scroll to second page labels.