swift234

[Conformance checking] Apply omit-needless-words for near-miss checking.

The differences between Swift 2 and Swift 3 names can be very
significant, when the Swift 2 names have a lot of restated type
information. These differences end up disabling the near-miss
heuristics because the magnitude of the change is so high. Therefore,
apply the omit-needless-words heuristics to the potential witness and
the requirement before scoring them.

Should finish up rdar://problem/25159872 for real.