Disambiguate definitions

[jyasskin]

Both Fetch and Network Error Logging define "network error", in different ways. NEL's should probably be spelled differently.

NEL also defines a "type" for network errors, but ought to scope it with data-dfn-for to avoid colliding with all the other types out there.

[igrigorik]

Hmm, yeah that makes sense, we do have different definitions.

@dcreager do you have bandwidth to tackle this one?

[clelland]

It would sound better, I think, if Fetch's concept were to be spelled "network error response", as it really is a response, rather than being the error condition itself. NEL tries to report on the actual error.

Alternately, if it's not possible to change that, then maybe NEL should rename network error -> network error condition

[jyasskin]

Given how widely Fetch's definition could be used, and how difficult it is to track down all the uses (speced/bikeshed#672), this spec probably can't get around needing to rename "network error" for the medium term, even if Fetch also renames it.