swift234

Use "cascading/non-" terms for dependencies instead of "private/non-".

"private" is a very overloaded term already. "Cascading" instead of
"non-private" is a bit more clear about what will happen with this sort
of lookup.

No functionality change. There are some double negatives I plan to clean
up in the next commit, but this one was supposed to be very mechanical.

Swift SVN r23969