net/http/httputil: use response controller in reverse proxy
Previously, the reverse proxy is unable to detect
the support for hijack or flush if those things
are residing in the response writer in a wrapped
manner.
The reverse proxy now makes use of the new http
response controller as the means to discover
the underlying flusher and hijacker associated
with the response writer, allowing wrapped flusher
and hijacker become discoverable.
Change-Id: I53acbb12315c3897be068e8c00598ef42fc74649
Reviewed-on: https://go-review.googlesource.com/c/go/+/468755
Run-TryBot: Damien Neil <dneil@google.com>
Auto-Submit: Damien Neil <dneil@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Damien Neil <dneil@google.com> Reviewed-by: Cherry Mui <cherryyz@google.com>