LibWeb: Implement '5.1. Headers class' from the Fetch API :^)

Userland/Libraries/LibWeb/Fetch/HeadersIterator.h

@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2022, Linus Groh <linusg@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibWeb/Bindings/Wrappable.h>
+#include <LibWeb/Fetch/Headers.h>
+
+namespace Web::Fetch {
+
+class HeadersIterator
+    : public Bindings::Wrappable
+    , public RefCounted<HeadersIterator> {
+public:
+    using WrapperType = Bindings::HeadersIteratorWrapper;
+
+    static NonnullRefPtr<HeadersIterator> create(Headers const& headers, JS::Object::PropertyKind iteration_kind)
+    {
+        return adopt_ref(*new HeadersIterator(headers, iteration_kind));
+    }
+
+    JS::ThrowCompletionOr<JS::Object*> next();
+
+    void visit_edges(JS::Cell::Visitor&);
+
+private:
+    HeadersIterator(Headers const& headers, JS::Object::PropertyKind iteration_kind)
+        : m_headers(headers)
+        , m_iteration_kind(iteration_kind)
+    {
+    }
+
+    Headers const& m_headers;
+    JS::Object::PropertyKind m_iteration_kind;
+    size_t m_index { 0 };
+};
+
+}
+
+namespace Web::Bindings {
+
+HeadersIteratorWrapper* wrap(JS::GlobalObject&, Fetch::HeadersIterator&);
+
+}