Auto merge of #17431 - emilio:restyle-hints-xbl, r=emilio

style: Cleanup after #17427, and remove extra-optimistic optimization added in #17429.

This just addresses my review comments in #17427, and removes a wrong optimization I added in #17429 thinking it was correct.

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components/style/gecko/wrapper.rs

@@ -1747,8 +1747,8 @@ impl<'le> ::selectors::Element for GeckoElement<'le> {
                 // If this element is the shadow root of an use-element shadow
                 // tree, according to the spec, we should not match rules
                 // cross the shadow DOM boundary.
-                e.get_local_name().as_ptr() == atom!("use").as_ptr() &&
-                e.get_namespace() == &*Namespace(atom!("http://www.w3.org/2000/svg"))
+                e.get_local_name() == &*local_name!("use") &&
+                e.get_namespace() == &*ns!("http://www.w3.org/2000/svg")
             },
             None => false,
         }

components/style/gecko_string_cache/namespace.rs

@@ -13,7 +13,8 @@ use string_cache::{Atom, WeakAtom};
 
 #[macro_export]
 macro_rules! ns {
-    () => { $crate::string_cache::Namespace(atom!("")) }
+    () => { $crate::string_cache::Namespace(atom!("")) };
+    ($s: tt) => { $crate::string_cache::Namespace(atom!($s)) };
 }
 
 /// A Gecko namespace is just a wrapped atom.

components/style/invalidation/element/invalidator.rs

@@ -333,7 +333,7 @@ impl<'a, 'b: 'a, E> TreeStyleInvalidator<'a, 'b, E>
         //
         // Since we keep the traversal flags in terms of the flattened tree,
         // we need to propagate it as appropriate.
-        if invalidated_child && child.parent_element() != Some(self.element) {
+        if invalidated_child {
             let mut current = child.traversal_parent();
             while let Some(parent) = current.take() {
                 if parent == self.element {