[css-anchor-position-1] Copy over the 'penultimate CB must precede the abspos' text from the next bullet point to cover similar cases here. #11030.

Author: tabatkins

css-anchor-position-1/Overview.bs

@@ -422,6 +422,10 @@ in anchor positioning.
 				and |possible anchor|'s [=containing block=] isn't.
 			* |positioned el|'s [=containing block=] is the [=initial containing block=],
 				and |possible anchor|'s [=containing block=] is generated by an element,
+				and the last [=containing block=] in |possible anchor|'s [=containing block chain=]
+				before reaching the [=initial containing block=]
+				is either not [=absolutely positioned=]
+				or precedes |positioned el| in the tree order.
 			* both elements' [=containing blocks=] are generated by elements,
 				and |positioned el|'s containing block
 				is an ancestor in the [=flat tree=]