[css-scroll-snap] Remove issue that's been addressed

Author: fantasai

css-scroll-snap/Overview.bs

@@ -733,10 +733,6 @@ Types of Scrolling Gestures {#scroll-types}
 		or another element's <a>snap position</a> might be chosen for that axis,
 		or that axis might not snap at all.
 
-		Issue: Define that the 1D snap position is only valid so long as you can see the element.
-		If it's off-screen, it should probably have no effect--that would be confusing,
-		to snap to a non-visible thing.
-
 	: <dfn export local-lt="2D" lt="2D snap position">2D snap position</dfn>
 	:: A <a>2d snap position</a> indicates a desired <a>snap position</a>
 		in both axises at once,