fix for incorrect composite literal grammar (issue found by ken)
fix for incorrect composite literal grammar
(issue found by ken)

R=go-dev, rsc
http://go/go-review/1025030

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