WebSocket support

[ricea]

This is related to issue #170, but I wanted to create a separate issue specifically for clarifying the behaviour around WebSockets.

My question is, are "wss" and "https" URLs considered equivalent for Network Error Logging? The Fetch Standard considers "wss" and "https" equivalent for cookies and other purposes (see https://websockets.spec.whatwg.org/#concept-websocket-establish), but it's not clear to me from the NEL standard whether that applies here.

Concretely:

• If a NEL header has been seen on a response to a request to https://example.com:8433/, should that configuration be used for a failed WebSocket connection to wss://example.com:8433/ ?
• Conversely, should a NEL header on a response from wss://example.com:8433/ affect requests to https://example.com:8433/ ?

[clelland]

Until we deal with either #166 or #170, I think the answer here is yes, the spec talks about "network requests" in a way that doesn't take their integration (or lack of) with fetch into account.

And I think that if we do resolve #166 by integrating more tightly with fetch, then WebSocket fetches would still participate in NEL, either by setting the NEL header in their responses, or by generating reports on failure.

So still yes, on both questions.

[clelland]

Is there a specific place in the spec that you think this could be clearer? Happy to patch in some text if you have some.

[ricea]

I think if #166 is resolved in favour of using Fetch, then the issue resolves itself. If not, it might be useful to add some extra words at that point.