[whatwg] <form method="DELETE"> and 307 redirects

[Adam Barth]

The spec lets sites submit forms with PUT or DELETE methods to their
origin server.  What happens if the server responds with a 307
redirect to a foreign origin?  Based on my reading of the fetch
algorithm, the browser will issue a PUT or DELETE request
(respectively) to the foreign origin.  It seems like we want to
generate a network error instead.

Adam