LibWeb: Start working on spec-aligned HTML scripting semantics

This patch adds HTML::Script and HTML::ClassicScript (subclass of the
former.)

Userland/Libraries/LibWeb/HTML/Scripting/Script.h

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/RefCounted.h>
+#include <AK/URL.h>
+
+namespace Web::HTML {
+
+// https://html.spec.whatwg.org/multipage/webappapis.html#concept-script
+class Script : public RefCounted<Script> {
+public:
+    virtual ~Script();
+
+    URL const& base_url() const { return m_base_url; }
+
+protected:
+    explicit Script(URL base_url);
+
+private:
+    URL m_base_url;
+};
+
+}