csp.js file throws client-side error with backend navigation

[haijian-ccc]

The 24.5-strict-csp branch was really hopeful for getting started with CSP. However when I start to add some backend navigation, it throws client-side errors and the url is not updated.

Steps to reproduce:

1. In DashboardView, add a button for backend navigation, add(new Button("Go to List", buttonClickEvent -> UI.getCurrent().navigate(ListView.class)));
2. Start the application, and open the Chrome Dev Tools.
3. Observe that upon clicking the button, it throws the errors in the Chrome Dev console, and the url is not updated.

[Legioth]

Looks like some additional definitions are needed nowadays. We might want to add those to the example but I would at the same time also encourage anyone using csp.js to get comfortable with doing it on your own since you will anyways need it for any add-on or similar that you're using.