[css-conditional-5] Explicitly allow tree counting functions #10982 (#12227)

Resolution:

#10982 (comment)

Author: lilles

css-conditional-5/Overview.bs

@@ -1160,6 +1160,9 @@ Size Container Features</h3>
 	in [=container query=] conditions
 	are evaluated based on the [=computed values=] of the [=query container=].
 
+	Tree counting functions ([[css-values-5#tree-counting]]) are evaluated against
+	the container element.
+
 	Note: This is different from the handling of relative units in [=media queries=].
 
 	Note: If [=custom property=] substitution results in an invalid value for the