style: Add gecko_pref annotation to the properties.

components/style/properties/shorthand/box.mako.rs

@@ -331,6 +331,7 @@ macro_rules! try_parse_one {
 </%helpers:shorthand>
 
 <%helpers:shorthand name="scroll-snap-type" products="gecko"
+                    gecko_pref="layout.css.scroll-snap.enabled"
                     sub_properties="scroll-snap-type-x scroll-snap-type-y"
                     spec="https://drafts.csswg.org/css-scroll-snap/#propdef-scroll-snap-type">
     use properties::longhands::scroll_snap_type_x;
@@ -360,6 +361,7 @@ macro_rules! try_parse_one {
 
 <%helpers:shorthand name="-moz-transform" products="gecko"
                     sub_properties="transform"
+                    gecko_pref="layout.css.prefixes.transforms"
                     flags="SHORTHAND_ALIAS_PROPERTY"
                     derive_serialize="True"
                     spec="Non-standard: https://developer.mozilla.org/en-US/docs/Web/CSS/transform">

components/style/properties/shorthand/inherited_text.mako.rs

@@ -46,6 +46,7 @@
 <%helpers:shorthand name="-webkit-text-stroke"
                     sub_properties="-webkit-text-stroke-width
                                     -webkit-text-stroke-color"
+                    gecko_pref="layout.css.prefixes.webkit"
                     products="gecko"
                     derive_serialize="True"
                     spec="https://compat.spec.whatwg.org/#the-webkit-text-stroke">

components/style/properties/shorthand/position.mako.rs

@@ -462,6 +462,7 @@
                     sub_properties="grid-template-rows grid-template-columns grid-template-areas
                                     grid-auto-rows grid-auto-columns grid-auto-flow"
                     spec="https://drafts.csswg.org/css-grid/#propdef-grid"
+                    gecko_pref="layout.css.grid.enabled"
                     products="gecko">
     use parser::Parse;
     use properties::longhands::{grid_auto_columns, grid_auto_rows, grid_auto_flow};