[css-anchor-position] Remove lingering mentions of fallback-bounds rects

Author: tabatkins

css-anchor-position-1/Overview.bs

@@ -855,14 +855,6 @@ we define:
 	Issue: Define the precise timing of the snapshot:
 	updated each frame,
 	before style recalc.
-
-	If |query el| has an [=additional fallback-bounds rect=],
-	similarly calculate the sum of [=scroll offsets=]
-	of all [=scroll container=] ancestors
-	of the element generating the [=additional fallback-bounds rect=],
-	up to but not including |query el|'s [=containing block=],
-	and subtract that summed offset
-	from the [=additional fallback-bounds rect's=] position.
 </div>
 
 
@@ -1401,10 +1393,6 @@ as part of a theoretical UA-controlled final cascade layer.
 		4. If |el rect| is not fully contained within |cb rect|,
 			[=iteration/continue=].
 
-		4. If |el| has an [=additional fallback-bounds rect=],
-			and |el rect| is not fully contained within it,
-			[=iteration/continue=].
-
 		5. Set |option| as |el|'s <dfn>last successful position option</dfn>.
 			Return |adjusted styles|.