[css-align] origin -> initial scroll position

Author: fantasai

css-align/Overview.bs

@@ -1609,7 +1609,7 @@ Determining the Baselines of a Box</h2>
 
 	For the purposes of finding the baselines of a box,
 	it and all its in-flow descendants with a scrolling mechanism (see the 'overflow' property)
-	must be considered as if scrolled to their origin.
+	must be considered as if scrolled to their initial scroll position.
 	Furthermore, if, in the case of a box with non-''visible'' overflow,
 	the resulting position of a first (last) baseline
 	is past a box's end (start) border edge,