Nav Scroll tabs breaks flex layouts

I've seen that it's using width: 99999px; by design to implement the scroll but this causes some issues when using the tabs inside a flex container.

We can reproduce this in the rc-tabs docs.

http://react-component.github.io/tabs/examples/activeKey.html

Change the container to display flex and add some padding like this:

You can see that the content inside the tab isn't respecting the padding of the container and it goes beyond the size of the page.

Removing the width on .rc-tabs-nav-scroll fixes the issue:

Note that this is actually really important, if there's any div that uses % widths inside the content or anything with position absolute, it'll be completely broken, the same applies to any kind of grid layout inside that.

Start with the rc-tabs activeKey documentation example and reproduce the issue by placing the tabs in a flex container with padding. Inspect the .rc-tabs-nav-scroll styles, especially its 99999px width, and verify the layout with percentage-width or absolutely positioned content. Done means the tabs respect the container bounds without breaking scrolling.