Make KeyCancellation independent of extraNatural (issue4014041)

[percival . music . ca]

This patch appears to be have been created in "reversed" fashion -- I'm
certain that you meant to *add* a new regtest, for example, instead of
*deleting* one.

I think that in the past 2 weeks, you've learned a lot about git and
codereview, so I'll just ask you to re-upload this patch.


http://codereview.appspot.com/4014041/