Steps to reproduce:

1. Load https://blog.wanderview.com and open devtools network monitor
2. Reload a few times
3. Note that the "highlighter-small.jpg" resource is marked as "(from ServiceWorker)".
4. Click on the resource and note that it has no service worker related timing information.

This resource is actually loaded from the memory cache.  It was initially loaded from the service worker when the memory cache was populated.  I think it would make most sense for the devtools to report that it loaded from memory cache since there will not be any observable FetchEvent in this case.

CL coming.