The Domino 8.5.3 server uses Dojo 1.6.1 for XPages. You should see this if you view the HTML source of a test application.
As an example, I see this in one of my applications:
"/xsp/.ibmxspres/dojoroot-1.6.1/dojo/dojo.js"
If you are going to create apps using Dojo Mobile then take a look at the Extension Library and the latest Upgrade Pack 1 for Domino 8.5.3. Both includes XPages Mobile controls.