[css-position-4] Remove the fragmentation thing entirely - fullscreening an element frag'd across a multicol makes it render fresh, so it's not in the multicol anymore...

Author: tabatkins

css-position-4/Overview.bs

@@ -382,12 +382,6 @@ are rendered with the following qualities:
 
 * Its parent stacking context is the root stacking context.
 
-* If the element generates multiple boxes due to fragmentation,
-	only the first such box is rendered;
-	additional boxes are discarded without rendering.
-
-	<!-- https://www.w3.org/Bugs/Public/show_bug.cgi?id=24523 -->
-
 * It is rendered as an atomic unit as if it were a sibling of the document's root.
 
 	Note: Ancestor elements with 'overflow', 'opacity', 'mask', etc. cannot affect it.