update origins considered by paired cascade for resolution in #6386

Author: delan

css-pseudo-4/Overview.bs

@@ -791,11 +791,9 @@ Highlight Colors</h4>
   when neither the originating element’s [=cascade=],
   nor those of any of the originating element’s ancestors,
   yield any highlight colors
-  of the [=author origin|author=],
-  [=animation origin|animation=],
-  or [=transition origin|transition=] origins.
+  of the [=author origin=].
   In other words,
-  when setting one “custom” highlight color,
+  when the author sets one “custom” highlight color,
   defaults for the other highlight color are suppressed.
 
   This does not preclude the UA