Name boolean arguments in src/compiler.

What would you prefer?

  adaptToMemberWithArgs(tree, qual, name, mode, false, false)

Or:

  adaptToMemberWithArgs(tree, qual, name, mode, reportAmbiguous = false, saveErrors = false)

I plan to apply the same treatment to the other modules, but these broad ranging commits don't age well, so let's start with this one.

Review by @paulp. Minor chuckles here: https://github.com/retronym/scala/pull/new/topic/bool-arg#L62L15