style: Remove -moz-binding, nsStyleDisplay::mBinding and similar.

Differential Revision: https://phabricator.services.mozilla.com/D50556

components/style/properties/gecko.mako.rs

@@ -276,11 +276,6 @@ impl ComputedValuesInner {
     pub fn get_raw_visited_style(&self) -> &Option<RawOffsetArc<ComputedValues>> {
         &self.visited_style
     }
-
-    #[allow(non_snake_case)]
-    pub fn has_moz_binding(&self) -> bool {
-        !self.get_box().gecko.mBinding.is_none()
-    }
 }
 
 <%def name="declare_style_struct(style_struct)">

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

@@ -630,18 +630,6 @@ ${helpers.predefined_type(
     gecko_ffi_name="mAppearance",
 )}
 
-${helpers.predefined_type(
-    "-moz-binding",
-    "url::UrlOrNone",
-    "computed::url::UrlOrNone::none()",
-    engines="gecko",
-    animation_value_type="none",
-    gecko_ffi_name="mBinding",
-    gecko_pref="layout.css.moz-binding.content.enabled",
-    enabled_in="chrome",
-    spec="Nonstandard (https://developer.mozilla.org/en-US/docs/Web/CSS/-moz-binding)",
-)}
-
 ${helpers.single_keyword(
     "-moz-orient",
     "inline block horizontal vertical",

components/style/properties/properties.mako.rs

@@ -3074,10 +3074,6 @@ impl ComputedValuesInner {
         self.rules.as_ref().unwrap()
     }
 
-    /// Whether this style has a -moz-binding value. This is always false for
-    /// Servo for obvious reasons.
-    pub fn has_moz_binding(&self) -> bool { false }
-
     #[inline]
     /// Returns whether the "content" property for the given style is completely
     /// ineffective, and would yield an empty `::before` or `::after`

components/style/traversal.rs

@@ -267,7 +267,6 @@ pub trait DomTraversal<E: TElement>: Sync {
         context: &mut StyleContext<E>,
         parent: E,
         parent_data: &ElementData,
-        is_initial_style: bool,
     ) -> bool {
         debug_assert!(
             parent.has_current_styles_for_traversal(parent_data, context.shared.traversal_flags)
@@ -279,21 +278,6 @@ pub trait DomTraversal<E: TElement>: Sync {
             return true;
         }
 
-        // Gecko-only XBL handling.
-        //
-        // When we apply the XBL binding during frame construction, we restyle
-        // the whole subtree again if the binding is valid, so assuming it's
-        // likely to load valid bindings, we avoid wasted work here, which may
-        // be a very big perf hit when elements with bindings are nested
-        // heavily.
-        if cfg!(feature = "gecko") &&
-            is_initial_style &&
-            parent_data.styles.primary().has_moz_binding()
-        {
-            debug!("Parent {:?} has XBL binding, deferring traversal", parent);
-            return true;
-        }
-
         return false;
     }
 
@@ -521,7 +505,7 @@ pub fn recalc_style_at<E, D, F>(
         is_servo_nonincremental_layout();
 
     traverse_children = traverse_children &&
-        !traversal.should_cull_subtree(context, element, &data, is_initial_style);
+        !traversal.should_cull_subtree(context, element, &data);
 
     // Examine our children, and enqueue the appropriate ones for traversal.
     if traverse_children {