Macros#calculateUndetparams is a no-op if there are no undetparams

[hrhino]

https://github.com/scala/scala/blob/546a57105e33678d9d0aba9da486006e4715924c/src/compiler/scala/tools/nsc/typechecker/Macros.scala#L848-859

  private def calculateUndetparams(expandee: Tree): scala.collection.mutable.Set[Symbol] =
    if (forced(expandee)) scala.collection.mutable.Set[Symbol]()
    else delayed.getOrElse(expandee, {
      val calculated = scala.collection.mutable.Set[Symbol]()
      expandee foreach (sub => {
        def traverse(sym: Symbol) = if (sym != null && (undetparams contains sym)) calculated += sym
        if (sub.symbol != null) traverse(sub.symbol)
        if (sub.tpe != null) sub.tpe foreach (sub => traverse(sub.typeSymbol))
      })
      macroLogVerbose("calculateUndetparams: %s".format(calculated))
      calculated
    })