io/router: account for parent clip areas when scrolling focus into view

Fixes: https://todo.sr.ht/~eliasnaur/gio/389
Signed-off-by: Elias Naur <mail@eliasnaur.com>

io/router/router.go

@@ -161,6 +161,8 @@ func (q *Router) RevealFocus(viewport image.Rectangle) {
 		return
 	}
 	bounds := q.key.queue.BoundsFor(focus)
+	area := q.key.queue.AreaFor(focus)
+	viewport = q.pointer.queue.ClipFor(area, viewport)
 
 	topleft := bounds.Min.Sub(viewport.Min)
 	topleft = max(topleft, bounds.Max.Sub(viewport.Max))