LibJS: Implement Sets using Maps

This implements ordered sets using Maps with a sentinel value, and
includes some extra set tests.
Fixes #11004.

Co-Authored-By: davidot <davidot@serenityos.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/Userland/Libraries/LibJS/Runtime/Set.cpp b/Userland/Libraries/LibJS/Runtime/Set.cpp
index dfaaf0b28a..32a11c0148 100644
--- a/Userland/Libraries/LibJS/Runtime/Set.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Set.cpp
@@ -15,6 +15,7 @@ Set* Set::create(GlobalObject& global_object)
 
 Set::Set(Object& prototype)
     : Object(prototype)
+    , m_values(*prototype.global_object().map_prototype())
 {
 }
 
@@ -25,8 +26,7 @@ Set::~Set()
 void Set::visit_edges(Cell::Visitor& visitor)
 {
     Base::visit_edges(visitor);
-    for (auto& value : m_values)
-        visitor.visit(value);
+    static_cast<Object&>(m_values).visit_edges(visitor);
 }
 
 }