Define referrerPolicy IDL attribute about webappsec-referrer-policy

[sc0ttbeardsley]

@annevk where should this be defined? Here? https://fetch.spec.whatwg.org/#referrerpolicy

[annevk]

It should be defined together with the content attribute.

You want to have something similar to https://w3c.github.io/webappsec-subresource-integrity/#element-interface-extensions except I see now that the language used there to define the IDL attributes is wrong. (The IDL is correct however, you want to use that as an example.)

The language you want is:

The referrerPolicy IDL attribute must reflect the referrerpolicy content attribute, limited to only known values.

[annevk]

(The alternative here is to instead patch HTML and define the attribute there. That is what we want to do in the long run I think. So the HTML vocabulaire remains self-contained.)

[jeisinger]

@estark37

[hsivonen]

Do the editors agree that the IDL attribute should exist as proposed by @annevk in some relevant spec? That is, can we implement it in Gecko and not have to bikeshed its existence or name later?

[jeisinger]

@hsivonen, yes - adding to the referrer policy spec