[preload-tests] Verify that preloads with a "fetch" `as` value have an empty destination (#4505)

@annevk - As discussed on https://github.com/whatwg/fetch/pull/442, here's the corresponding test. Note that it fails in all current implementations.

View on GitHub: https://github.com/w3c/web-platform-tests/pull/4505

Received on Wednesday, 4 January 2017 14:35:32 UTC