LibWeb: Extract some Internals functionality to a base class

This will just allow re-using these definitions on other internal pages.

Libraries/LibWeb/Internals/InternalsBase.cpp

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2025, Tim Flynn <trflynn89@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/HTML/Scripting/Environments.h>
+#include <LibWeb/HTML/Window.h>
+#include <LibWeb/Internals/InternalsBase.h>
+#include <LibWeb/Page/Page.h>
+
+namespace Web::Internals {
+
+GC_DEFINE_ALLOCATOR(InternalsBase);
+
+InternalsBase::InternalsBase(JS::Realm& realm)
+    : Bindings::PlatformObject(realm)
+{
+}
+
+InternalsBase::~InternalsBase() = default;
+
+HTML::Window& InternalsBase::window() const
+{
+    return as<HTML::Window>(HTML::relevant_global_object(*this));
+}
+
+Page& InternalsBase::page() const
+{
+    return window().page();
+}
+
+}