LibWeb: Add a helper class to work around empty execution context stack

We've peppered this workaround around the code base as needed in a few
different ways. This adds a helper class to perform this workaround in
order to simplify doing so, and ensure cleanup occurs in a RAII fashion.
This also makes it easier to grep for places where this workaround is
employed.

Userland/Libraries/LibWeb/HTML/Scripting/TemporaryExecutionContext.cpp

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2023, Tim Flynn <trflynn89@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/HTML/Scripting/Environments.h>
+#include <LibWeb/HTML/Scripting/TemporaryExecutionContext.h>
+
+namespace Web::HTML {
+
+TemporaryExecutionContext::TemporaryExecutionContext(EnvironmentSettingsObject& environment_settings)
+    : m_environment_settings(environment_settings)
+{
+    m_environment_settings.prepare_to_run_script();
+}
+
+TemporaryExecutionContext::~TemporaryExecutionContext()
+{
+    m_environment_settings.clean_up_after_running_script();
+}
+
+}