go.net/spdy: fix typo
go.net/spdy: fix typo

R=golang-dev, dchest
CC=golang-dev
http://codereview.appspot.com/6595043

ssor/go.net,fernandez14/go.net,go-mirrors/go.net,polydawn-ports/go.net,gigq/go.net,andrewzeneski/go.net