http: Allow cookies with negative Max-Age attribute as these are allowed by RFC 6265 sec 5.2.2.
http: Allow cookies with negative Max-Age attribute as these are
allowed by RFC 6265 sec 5.2.2.

R=golang-dev, adg
CC=golang-dev
http://codereview.appspot.com/5533083

Committer: Andrew Gerrand <395a7d33bec8475c9b83b7d440f141bcbd994aa5@golang.org>

firebitsbr/golang-old,wesolows/golang,firebitsbr/golang-old,wesolows/golang-old,wesolows/golang,wesolows/golang,wesolows/golang-old,firebitsbr/golang-old,wesolows/golang-old,firebitsbr/golang-old,wesolows/golang-old,wesolows/golang-old,firebitsbr/golang-old,wesolows/golang,firebitsbr/golang-old,firebitsbr/golang-old,firebitsbr/golang-old,wesolows/golang-old,wesolows/golang-old,wesolows/golang,wesolows/golang,wesolows/golang