[x/tour] tour: ignore pageup and pagedown if ctrl is pressed
[x/tour] tour: ignore pageup and pagedown if ctrl is pressed

Fixes golang/go#11963

Change-Id: I5fb1e598042daa0a3c9137468fae9e7ce55dbce7
Reviewed-on: https://go-review.googlesource.com/13137
Reviewed-by: Andrew Gerrand <395a7d33bec8475c9b83b7d440f141bcbd994aa5@golang.org>
X-Tour-Commit: 268412c9c85c5fee71dd973e5fea0a14ca0e9c72

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