Scrollable regions should pass when there is an open modal [0ssw9k]

[WilcoFiers]

The Scrollable content can be reached with sequential focus navigation
, rule does not account for scrollable regions that are covered by the backdrop of a modal. While a model is open, it is perfectly reasonable for scrollable regions not to have focusable elements inside them.

[Jym77]

I guess it should more generally hook on inert subtrees, which includes being blocked by a modal.

[giacomo-petri]

Do we want to adjust the applicability to make this scenario inapplicable, or should we find a way to include it in the passing examples? (The first option is easier 😆)

Edit: Actually, the second option is more accurate. I'll go with it.