Accessibility issue in FocusTrapZone

[cnamal]

Accessibility insights shows the following error with FocusTrapZones:

aria-hidden-focus: ARIA hidden element must not contain focusable elements WCAG 4.1.2

I believe the issue is on the following line:
https://github.com/OfficeDev/office-ui-fabric-react/blob/24937f2580a0bd608c7114d1afd43b4536f8c74d/packages/office-ui-fabric-react/src/components/FocusTrapZone/FocusTrapZone.tsx#L74

I don't think the aria-hidden is necessary since the divs it's applied to are empty, though I might be mistaken.

[joschect]

@cnamal Thanks for submitting this ticket! I'll take a look and see if I can figure out why that got added in the first place.

[joschect]

Looks like this was added in #8274

[joschect]

This was added because scan mode should not be stopping at the bumpers. I'll test and verify that it needs to be there

[cnamal]

Resolved by #9019