contract/website_portal_contract/demo/assets_demo.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright 2017 LasLabs Inc.
     License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl). -->

<odoo>

    <template id="assets_frontend_demo" inherit_id="website.assets_frontend">
        <xpath expr=".">
            <script type="text/javascript"
                    src="/website_portal_contract/static/src/js/tour_test_contract.js" />
        </xpath>
    </template>

</odoo>