Custom logic from request.go has been removed.

Created by running: “go run gen.go -core” from x/text
at fc7fa097411d30e6708badff276c4c164425590c.

Fixes golang/go#17268

Change-Id: Ie440d6ae30288352283d303e5126e5837f11bece
Reviewed-on: https://go-review.googlesource.com/37111
Run-TryBot: Marcel van Lohuizen <mpvl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>