LibWeb: Make StyleSheet and CSSStyleSheet GC-allocated

Author: https://github.com/awesomekling
Commit: 5d60212076
Pull-request: https://github.com/SerenityOS/serenity/pull/14816
Reviewed-by: https://github.com/ADKaster
Reviewed-by: https://github.com/linusg ✅

Userland/Libraries/LibWeb/HTML/HTMLStyleElement.h

@@ -24,11 +24,12 @@ public:
 
     void update_a_style_block();
 
-    RefPtr<CSS::CSSStyleSheet> sheet() const;
+    CSS::CSSStyleSheet* sheet();
+    CSS::CSSStyleSheet const* sheet() const;
 
 private:
     // https://www.w3.org/TR/cssom/#associated-css-style-sheet
-    RefPtr<CSS::CSSStyleSheet> m_associated_css_style_sheet;
+    JS::Handle<CSS::CSSStyleSheet> m_associated_css_style_sheet;
 };
 
 }