style: Kill -servo-under-display-none.

Signed-off-by: Emilio Cobos Álvarez <emilio@crisal.io>

components/layout/construct.rs

@@ -1451,7 +1451,7 @@ impl<'a, ConcreteThreadSafeLayoutNode> PostorderNodeMutTraversal<ConcreteThreadS
         node.insert_flags(HAS_NEWLY_CONSTRUCTED_FLOW);
 
         // Bail out if this node has an ancestor with display: none.
-        if node.style(self.style_context()).get_inheritedbox()._servo_under_display_none.0 {
+        if node.style(self.style_context()).is_in_display_none_subtree() {
             self.set_flow_construction_result(node, ConstructionResult::None);
             return;
         }

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

@@ -185,7 +185,6 @@
                                    context: &mut computed::Context) {
             longhands::_servo_display_for_hypothetical_box::derive_from_display(context);
             longhands::_servo_text_decorations_in_effect::derive_from_display(context);
-            longhands::_servo_under_display_none::derive_from_display(context);
         }
     % endif
 

components/style/properties/longhand/inherited_box.mako.rs

@@ -249,43 +249,3 @@ ${helpers.single_keyword("image-rendering",
         }
     }
 </%helpers:longhand>
-
-// Used in the bottom-up flow construction traversal to avoid constructing flows for
-// descendants of nodes with `display: none`.
-<%helpers:longhand name="-servo-under-display-none"
-                   derived_from="display"
-                   products="servo"
-                   animation_value_type="none"
-                   spec="Nonstandard (internal layout use only)">
-    use std::fmt;
-    use style_traits::ToCss;
-
-    #[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
-    #[cfg_attr(feature = "servo", derive(Deserialize, HeapSizeOf, Serialize))]
-    #[derive(Clone, Copy, Debug, Eq, PartialEq, ToComputedValue)]
-    pub struct SpecifiedValue(pub bool);
-
-    pub mod computed_value {
-        pub type T = super::SpecifiedValue;
-    }
-
-    pub fn get_initial_value() -> computed_value::T {
-        SpecifiedValue(false)
-    }
-
-    impl ToCss for SpecifiedValue {
-        fn to_css<W>(&self, _: &mut W) -> fmt::Result where W: fmt::Write {
-            Ok(()) // Internal property
-        }
-    }
-
-    #[inline]
-    pub fn derive_from_display(context: &mut Context) {
-        use super::display::computed_value::T as Display;
-
-        if context.style().get_box().clone_display() == Display::none {
-            context.builder
-                .set__servo_under_display_none(SpecifiedValue(true));
-        }
-    }
-</%helpers:longhand>

components/style/properties/properties.mako.rs

@@ -2026,6 +2026,13 @@ impl ComputedValues {
     pub fn visited_rules(&self) -> Option<<&StrongRuleNode> {
         self.visited_style.as_ref().and_then(|s| s.rules.as_ref())
     }
+
+    /// Returns whether we're in a display: none subtree.
+    pub fn is_in_display_none_subtree(&self) -> bool {
+        use properties::computed_value_flags::IS_IN_DISPLAY_NONE_SUBTREE;
+
+        self.flags.contains(IS_IN_DISPLAY_NONE_SUBTREE)
+    }
 }
 
 #[cfg(feature = "servo")]

components/style/servo/restyle_damage.rs

@@ -198,7 +198,6 @@ fn compute_damage(old: &ComputedValues, new: &ComputedValues) -> ServoRestyleDam
                        REFLOW, RECONSTRUCT_FLOW], [
         get_box.clear, get_box.float, get_box.display, get_box.position, get_counters.content,
         get_counters.counter_reset, get_counters.counter_increment,
-        get_inheritedbox._servo_under_display_none,
         get_list.quotes, get_list.list_style_type,
 
         // If these text or font properties change, we need to reconstruct the flow so that