LibJS: Add the WeakSet built-in object

Author: https://github.com/IdanHo
Commit: 8b6beac5ce
Pull-request: https://github.com/SerenityOS/serenity/pull/7954
Reviewed-by: https://github.com/linusg

Userland/Libraries/LibJS/Runtime/WeakSetConstructor.h

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibJS/Runtime/NativeFunction.h>
+
+namespace JS {
+
+class WeakSetConstructor final : public NativeFunction {
+    JS_OBJECT(WeakSetConstructor, NativeFunction);
+
+public:
+    explicit WeakSetConstructor(GlobalObject&);
+    virtual void initialize(GlobalObject&) override;
+    virtual ~WeakSetConstructor() override;
+
+    virtual Value call() override;
+    virtual Value construct(Function&) override;
+
+private:
+    virtual bool has_constructor() const override { return true; }
+};
+
+}