Tests for moving focus by pressing tab key across shadow boundaries.
To manually test, press tab key six times then shift+tab six times.
It should traverse focusable elements in the increasing numerical order and then in the reverse order.
Slot shouldn't be focused.
Slot shouldn't be focused.
This text shouldn't appear.
Slot shouldn't be focused.
2. No host child is assigned to slot3.
3. Inner Shadow Host.
Slot shouldn't be focused.
Slot shouldn't be focused.
This text shouldn't appear.
4. Assigned to slot4.
This text shouldn't appear. slot5 is in the fallback content of slot4 which has assigned nodes.