go-tour: remove built-in types from syntax highlighting keywords list
go-tour: remove built-in types from syntax highlighting keywords list

Fixes #40.

R=adg
CC=golang-dev
https://golang.org/cl/12975043

raindev/tour,rofrol/go-tour-pl,phoorichet/tour,golang/tour,rofrol/go-tour-pl,dupoxy/go-tour-fr,LaPingvino/go-tour-nl,bbandaru/tour,ybin/tour,ybin/tour,LaPingvino/go-tour-eo,campoy/go-tour-ua,golians/tour,golians/tour,Jasperste/tour,campoy/go-tour-ua,scryner/tour,phoorichet/tour,shuLhan/tour,campoy/go-tour-ua,scryner/tour,Go-zh/tour,shuLhan/go-tour-id,scryner/tour,Jasperste/tour,tamnd/tour,phoorichet/tour,tamnd/tour,shuLhan/tour,Jasperste/tour,Go-zh/tour,rofrol/go-tour-pl,Go-zh/tour,tamnd/tour,zorion/go-tour-ca,LaPingvino/go-tour-nl,scryner/tour,LaPingvino/go-tour-eo,zorion/go-tour-ca,LaPingvino/go-tour-nl,ybin/tour,golians/tour,LaPingvino/go-tour-eo,dupoxy/go-tour-fr,bbandaru/tour,bbandaru/tour,shuLhan/tour,Go-zh/tour,shuLhan/go-tour-id,shuLhan/go-tour-id,raindev/tour,dupoxy/go-tour-fr,raindev/tour