[css-anchor-position] Remove issue, already resolved by 'position-visibility'

Author: tabatkins

css-anchor-position-1/Overview.bs

@@ -1677,15 +1677,6 @@ based on the position fallback it's using,
 allowing many cases not allowed by this restricted list
 to be handled.
 
-Issue(#7758): Would be useful to be able to detect
-when your anchor(s) are fully off-screen
-and suppress your display entirely.
-For example, tooltips living outside the scroller
-holding the text they're anchored to
-don't want to just hover over arbitrary parts of the page
-because their anchor happens to have that position
-relative to the scrollport.
-
 Note: If multiple elements using different anchors
 want to use the same fallback positioning,
 just relative to their own anchor elements,