LibWeb: Add XMLDocument stub

Required by old versions of Pixi.js's XMLFormat bitmap font loader.
db824181dc/packages/text-bitmap/src/formats/XMLFormat.ts (L16)

Userland/Libraries/LibWeb/DOM/Document.h

@@ -472,9 +472,9 @@ protected:
     virtual JS::ThrowCompletionOr<void> initialize(JS::Realm&) override;
     virtual void visit_edges(Cell::Visitor&) override;
 
-private:
     Document(JS::Realm&, AK::URL const&);
 
+private:
     // ^HTML::GlobalEventHandlers
     virtual EventTarget& global_event_handlers_to_event_target(FlyString const&) final { return *this; }
 

Userland/Libraries/LibWeb/DOM/XMLDocument.cpp

@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2023, Luke Wilde <lukew@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/Bindings/XMLDocumentPrototype.h>
+#include <LibWeb/DOM/XMLDocument.h>
+
+namespace Web::DOM {
+
+XMLDocument::XMLDocument(JS::Realm& realm, AK::URL const& url)
+    : Document(realm, url)
+{
+}
+
+JS::ThrowCompletionOr<void> XMLDocument::initialize(JS::Realm& realm)
+{
+    MUST_OR_THROW_OOM(Base::initialize(realm));
+    set_prototype(&Bindings::ensure_web_prototype<Bindings::XMLDocumentPrototype>(realm, "XMLDocument"));
+
+    return {};
+}
+
+}

Userland/Libraries/LibWeb/DOM/XMLDocument.h

@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2023, Luke Wilde <lukew@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibWeb/DOM/Document.h>
+
+namespace Web::DOM {
+
+class XMLDocument final : public Document {
+    WEB_PLATFORM_OBJECT(XMLDocument, Document);
+
+public:
+    virtual ~XMLDocument() override = default;
+
+private:
+    XMLDocument(JS::Realm& realm, AK::URL const& url);
+
+    virtual JS::ThrowCompletionOr<void> initialize(JS::Realm&) override;
+};
+
+}

Userland/Libraries/LibWeb/DOM/XMLDocument.idl

@@ -0,0 +1,5 @@
+#import <DOM/Document.idl>
+
+[Exposed=Window]
+interface XMLDocument : Document {
+};