Accessibility issues on WindowScroller

[devcer]

Bug Report

Please include either a failing unit test or a simple repro. You can start by forking this Code Sandbox: https://codesandbox.io/s/03qpzq1p9p?module=%2FExample.js

What is the current behavior?

• Go to https://bvaughn.github.io/react-virtualized/#/components/WindowScroller
• Open Devtools and click on Lighthouse tab
• Run the accessibility tests for desktop version
• The tests fails with role="grid" container saying Elements with an ARIA [role] that require children to contain a specific [role] are missing some or all of those required children.

What is the expected behavior?

WindowScroller should be web accessible

Which versions of React and react-virtualized, and which browser / OS are affected by this issue? Did this work in previous versions of react-virtualized?

Browser	Several
OS	Several
React	17.0.1 and may be Several
React DOM	16.13.0 and may be Several
react-virtualized	9.22.3 and may be Several