[ServiceWorker] Navigate and redirects (#654)

HTML's navigate algorithm invokes fetch and asks it to not follow redirects. Service workers however do not have this primitive so will follow redirects. This results in e.g. a request for `/foo` ending up with a response from some other origin potentially. I guess that's all okay?

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Reply to this email directly or view it on GitHub:
https://github.com/slightlyoff/ServiceWorker/issues/654