Remove postorder traversal from layout 2020 during styling

components/layout_2020/traversal.rs

@@ -45,23 +45,26 @@ where
     ) where
         F: FnMut(E::ConcreteNode),
     {
-        unsafe { node.initialize_data() };
-
+        unsafe {
+            node.initialize_data();
             if !node.is_text_node() {
                 let el = node.as_element().unwrap();
                 let mut data = el.mutate_data().unwrap();
                 recalc_style_at(self, traversal_data, context, el, &mut data, note_child);
-        }
-    }
-
-    fn process_postorder(&self, _style_context: &mut StyleContext<E>, node: E::ConcreteNode) {
-        if let Some(el) = node.as_element() {
-            unsafe {
                 el.unset_dirty_descendants();
             }
         }
     }
 
+    #[inline]
+    fn needs_postorder_traversal() -> bool {
+        false
+    }
+
+    fn process_postorder(&self, _style_context: &mut StyleContext<E>, _node: E::ConcreteNode) {
+        panic!("this should never be called")
+    }
+
     fn text_node_needs_traversal(node: E::ConcreteNode, parent_data: &ElementData) -> bool {
         node.get_style_and_layout_data().is_none() || !parent_data.damage.is_empty()
     }