LibJS+LibWeb: Use new Cell::Visitor helpers to avoid manual iteration

Author: https://github.com/awesomekling
Commit: 53d0dd4a2e
Pull-request: https://github.com/SerenityOS/serenity/pull/23971
Reviewed-by: https://github.com/trflynn89

Userland/Libraries/LibWeb/HTML/Parser/StackOfOpenElements.cpp

@@ -16,8 +16,7 @@ StackOfOpenElements::~StackOfOpenElements() = default;
 
 void StackOfOpenElements::visit_edges(JS::Cell::Visitor& visitor)
 {
-    for (auto& element : m_elements)
-        visitor.visit(element);
+    visitor.visit(m_elements);
 }
 
 bool StackOfOpenElements::has_in_scope_impl(FlyString const& tag_name, Vector<FlyString> const& list) const