Make Range.numRangeElements private again.
Make Range.numRangeElements private again.

It was made private in 4c2f6f3cb1e0eee11facae8c44e3cd7db11378f1,
but it was reverted to public in the big collection overhaul, in
878e7d3e0d14633d19bac47dc9b532a54eab6379. I believe this was an
accident, so here is a commit to make it private again.

martijnhoekstra/scala,martijnhoekstra/scala,martijnhoekstra/scala,lrytz/scala,scala/scala,lrytz/scala,lrytz/scala,lrytz/scala,scala/scala,scala/scala,scala/scala,lrytz/scala,lrytz/scala,martijnhoekstra/scala,scala/scala,scala/scala,martijnhoekstra/scala,martijnhoekstra/scala