Should text nodes be ignored by aria-required-children?

The following code is passing the `aria-required-children` rule. I'm not sure whether it should, we should do some testing here. I expect assistive tech aren't going to allow proper keyboard navigation without a row / gridcell role on that last div. We'll see.

The reason this was raised is if you put `tabindex="0"` on that last div, it now gets reported as a failure. That's an inconsistency that's difficult to explain.

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