Allow navigating back to the original page without doing a full reload

   // @todo In case of navigating back to the original page, we don't have any
   // state that we can restore, so we need to reload the page. Improve this.

Once this is dealt with, we have one special case less to deal with, which would simplify #2705363: Fragments URLs fail: local fragments cause unnecessary page load, remote fragments cause HTTP 500 response.