http2: remove Transport.Fallback

We decided to glue together the HTTP/1 and HTTP/2 Transports in the
other direction, having the HTTP/1 code (net/http.Transport) start the
flow.

Remove the http2 Transport.Fallback for now, rather than leaving it
half implemented.

For background, see https://golang.org/cl/16090

Updates golang/go#6891

Change-Id: I511bc6d35a1a9a8e20010bd95ff694a894f42aa4
Reviewed-on: https://go-review.googlesource.com/16181
Reviewed-by: Andrew Gerrand <adg@golang.org>
1 file changed