title: When does PageTransitionEvent.persisted evaluate to true?
body: <p>I'm trying to detect if my current page is loaded from cache or is a fresh copy.</p>
  
  <p>I have the onPageShow callback registered on my body tag.
  I can see it being triggered, but I cannot produce a circumstance where the event.persisted is actually true.</p>
  
  <p>I've even put firefox in offline mode and I see the response being fetched from cache on the network tab but event.persisted is still false.</p>