From 038e0ceee7497bb12c08d00cd21dea762fbdb1ed Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Sat, 16 Mar 2024 08:03:46 +0100
Subject: [PATCH] LibWeb: Avoid copying the CSS @namespace every time we run a
 selector

---
 Userland/Libraries/LibWeb/CSS/CSSStyleSheet.h   | 2 ++
 Userland/Libraries/LibWeb/CSS/StyleComputer.cpp | 6 +++---
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/Userland/Libraries/LibWeb/CSS/CSSStyleSheet.h b/Userland/Libraries/LibWeb/CSS/CSSStyleSheet.h
index 46e1ce4aca8..fc102319eaa 100644
--- a/Userland/Libraries/LibWeb/CSS/CSSStyleSheet.h
+++ b/Userland/Libraries/LibWeb/CSS/CSSStyleSheet.h
@@ -65,6 +65,8 @@ public:
     void set_style_sheet_list(Badge<StyleSheetList>, StyleSheetList*);
 
     Optional<FlyString> default_namespace() const;
+    JS::GCPtr<CSSNamespaceRule> default_namespace_rule() const { return m_default_namespace_rule; }
+
     Optional<FlyString> namespace_uri(StringView namespace_prefix) const;
 
     Optional<URL> base_url() const { return m_base_url; }
diff --git a/Userland/Libraries/LibWeb/CSS/StyleComputer.cpp b/Userland/Libraries/LibWeb/CSS/StyleComputer.cpp
index de570b6c85f..d38b4b855d3 100644
--- a/Userland/Libraries/LibWeb/CSS/StyleComputer.cpp
+++ b/Userland/Libraries/LibWeb/CSS/StyleComputer.cpp
@@ -295,9 +295,9 @@ StyleComputer::RuleCache const& StyleComputer::rule_cache_for_cascade_origin(Cas
 [[nodiscard]] static bool filter_namespace_rule(DOM::Element const& element, MatchingRule const& rule)
 {
     // FIXME: Filter out non-default namespace using prefixes
-    auto namespace_uri = rule.sheet->default_namespace();
-    if (namespace_uri.has_value() && namespace_uri.value() != element.namespace_uri()) {
-        return false;
+    if (auto namespace_rule = rule.sheet->default_namespace_rule()) {
+        if (namespace_rule->namespace_uri() != element.namespace_uri())
+            return false;
     }
     return true;
 }