Stop pointless duplicate requests for some static resources in the service worker
Stop pointless duplicate requests for some static resources in the service worker

stev-0/bustimes.org.uk,jclgoodwin/bustimes.org.uk,stev-0/bustimes.org.uk,jclgoodwin/bustimes.org.uk,stev-0/bustimes.org.uk,stev-0/bustimes.org.uk,jclgoodwin/bustimes.org.uk,jclgoodwin/bustimes.org.uk,stev-0/bustimes.org.uk