swift234

Omit needless words: split the base name when the first parameter is defaulted.

Split the base name at the last preposition, but *only* when the first
parameter is defaulted, because defaulted arguments might not show up
at the call site and the longer base name can feel odd in such
cases. With this, stop avoiding the argument label "with": it's fine
when we have actual context at the call site, and the "with: nil" case
no longer happens now that we're defaulting nil.

Swift SVN r32098