style:- Remove column-span pref in column.mako.rs.

Differential Revision: https://phabricator.services.mozilla.com/D58399

components/style/properties/longhands/column.mako.rs

@@ -69,17 +69,14 @@ ${helpers.predefined_type(
     spec="https://drafts.csswg.org/css-multicol/#propdef-column-rule-color",
 )}
 
-// FIXME: Remove enabled_in="ua" once column-span is enabled on nightly (bug 1423383).
 ${helpers.single_keyword(
     "column-span",
     "none all",
     engines="gecko",
     animation_value_type="discrete",
     gecko_enum_prefix="StyleColumnSpan",
-    gecko_pref="layout.css.column-span.enabled",
-    enabled_in="ua",
     spec="https://drafts.csswg.org/css-multicol/#propdef-column-span",
-    extra_prefixes="moz:layout.css.column-span.enabled",
+    extra_prefixes="moz",
 )}
 
 ${helpers.predefined_type(