[x/tour] go-tour: don't reset code on slide change
[x/tour] go-tour: don't reset code on slide change

R=bradfitz
CC=golang-dev
https://golang.org/cl/6819060
X-Tour-Commit: 7ba7c54b28a8cf5e6d234f06e704317e057ed327

golang/website,golang/website,golang/website,golang/website,golang/website,golang/website,golang/website