Why this change?
We were verifying that a url for a section link in a custom sidebar
section is valid by passing the url string to `Router#recognize`.
If a `rootURL` has been set on the router, the url string that is passed
to `Router#recognize` has to start with the `rootURL`.
This commit fixes the problem by ensuring that `RouteInfoHelper` adds
the application subfolder path before calling `Router#recognize` on the
url string.
752bb29415