social/mail_quoted_reply/templates/assets.xml

<?xml version="1.0" encoding="utf-8" ?>
<!-- Copyright 2014-2015 Grupo ESOC <http://www.grupoesoc.es>
     License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html). -->
<odoo>

<template
        id="assets_backend"
        name="mail_quoted_reply assets"
        inherit_id="web.assets_backend"
    >
    <xpath expr="." position="inside">

        <script
                type="text/javascript"
                src="/mail_quoted_reply/static/src/js/mail_message_reply.js"
            />
    </xpath>
</template>
</odoo>