style: Avoid some allocations in selector serialization.

The allocations in display_to_css_identifier show up in the profiles of
bug 1675628.

Differential Revision: https://phabricator.services.mozilla.com/D97856

2 files changed, 1 insertions, 16 deletions

diff --git a/components/style/gecko_string_cache/mod.rs b/components/style/gecko_string_cache/mod.rs
index e9208a5e32e..a6cf017877d 100644
--- a/components/style/gecko_string_cache/mod.rs
+++ b/components/style/gecko_string_cache/mod.rs
@@ -42,12 +42,6 @@ pub mod namespace;
 
 pub use self::namespace::{Namespace, WeakNamespace};
 
-macro_rules! local_name {
-    ($s:tt) => {
-        atom!($s)
-    };
-}
-
 /// A handle to a Gecko atom. This is a type that can represent either:
 ///
 ///  * A strong reference to a dynamic atom (an `nsAtom` pointer), in which case
diff --git a/components/style/gecko_string_cache/namespace.rs b/components/style/gecko_string_cache/namespace.rs
index 72de229f1d7..1acf04c93ff 100644
--- a/components/style/gecko_string_cache/namespace.rs
+++ b/components/style/gecko_string_cache/namespace.rs
@@ -47,18 +47,9 @@ impl PrecomputedHash for Namespace {
 }
 
 /// A Gecko WeakNamespace is a wrapped WeakAtom.
-#[derive(Hash)]
+#[derive(Hash, Deref)]
 pub struct WeakNamespace(WeakAtom);
 
-impl Deref for WeakNamespace {
-    type Target = WeakAtom;
-
-    #[inline]
-    fn deref(&self) -> &WeakAtom {
-        &self.0
-    }
-}
-
 impl Deref for Namespace {
     type Target = WeakNamespace;