[css-content-3] Fix off-by-one error in quote depth of closing quotes. #2506

Author: fantasai

css-content-3/Overview.bs

@@ -487,7 +487,7 @@ The *-quote values of the content property</h4>
 	Which pair of quotes is used depends on the nesting level of quotes
 	(the <dfn>quote depth</dfn>):
 	the number of occurrences of ''open-quote'' in all generated text before the current occurrence,
-	minus the number of occurrences of ''close-quote''.
+	minus the number of occurrences of ''close-quote'' in all generated text before and including the current occurence.
 	If the depth is 0, the first pair is used,
 	if the depth is 1, the second pair is used, etc.
 	If the depth is greater than the number of pairs,