LibWeb: Implement Geometry::DOMRectList

Implement DOMRectList that is used as a return type of
getClientRects functions on Element and Range.

Userland/Libraries/LibWeb/Geometry/DOMRectList.h

@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2022, DerpyCrabs <derpycrabs@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Noncopyable.h>
+#include <AK/NonnullRefPtrVector.h>
+#include <AK/RefCounted.h>
+#include <AK/Vector.h>
+#include <LibWeb/Bindings/Wrappable.h>
+#include <LibWeb/Forward.h>
+#include <LibWeb/Geometry/DOMRect.h>
+
+namespace Web::Geometry {
+
+// https://drafts.fxtf.org/geometry-1/#DOMRectList
+class DOMRectList final
+    : public RefCounted<DOMRectList>
+    , public Bindings::Wrappable {
+    AK_MAKE_NONCOPYABLE(DOMRectList);
+    AK_MAKE_NONMOVABLE(DOMRectList);
+
+public:
+    using WrapperType = Bindings::DOMRectListWrapper;
+
+    static NonnullRefPtr<DOMRectList> create(NonnullRefPtrVector<DOMRect>&& rects)
+    {
+        return adopt_ref(*new DOMRectList(move(rects)));
+    }
+
+    ~DOMRectList() = default;
+
+    u32 length() const;
+    DOMRect const* item(u32 index) const;
+
+    bool is_supported_property_index(u32) const;
+
+private:
+    DOMRectList(NonnullRefPtrVector<DOMRect>&& rects);
+
+    NonnullRefPtrVector<DOMRect> m_rects;
+};
+
+}