style: Remove the layout.css.scrollbar-width.enabled and layout.css.scrollbar-color.enabled prefs.

Differential Revision: https://phabricator.services.mozilla.com/D78400

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

@@ -77,13 +77,7 @@ ${helpers.predefined_type(
     "Default::default()",
     engines="gecko",
     spec="https://drafts.csswg.org/css-scrollbars-1/#scrollbar-color",
-    gecko_pref="layout.css.scrollbar-color.enabled",
-    # Surprisingly, yes the computed value of scrollbar-color has no effect on
-    # Gecko scrollbar elements, since the value only matters on the scrollable
-    # element itself.
-    has_effect_on_gecko_scrollbars=False,
     animation_value_type="ScrollbarColor",
     boxed=True,
     ignored_when_colors_disabled=True,
-    enabled_in="chrome",
 )}

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

@@ -27,8 +27,6 @@ ${helpers.single_keyword(
     engines="gecko",
     gecko_enum_prefix="StyleScrollbarWidth",
     animation_value_type="discrete",
-    gecko_pref="layout.css.scrollbar-width.enabled",
-    enabled_in="chrome",
     spec="https://drafts.csswg.org/css-scrollbars-1/#scrollbar-width"
 )}