[ServiceWorker] Should mixed content always be blocked? (#813)

Currently, trying to fetch content served by HTTP inside a service worker results in the request being blocked by the UA. Is this the expected behaviour? If so, which parts of the current specification support it?

I found this comment in a Chrome bug, referring to that:
https://code.google.com/p/chromium/issues/detail?id=448672#c4

It says fetch is not an optionally blockable request context but the [_should fetching request be blocked as mixed content_ algorithm](https://w3c.github.io/webappsec-mixed-content/#should-block-fetch) and [should response to request be blocked as mixed content](https://w3c.github.io/webappsec-mixed-content/#should-block-response) state [passthrough requests](https://w3c.github.io/webappsec-mixed-content/#passthrough-request) should be **allowed** (maybe with an opaque response, but that's another story).

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Reply to this email directly or view it on GitHub:
https://github.com/slightlyoff/ServiceWorker/issues/813