@specialized breaks polymorphic dispatch

I just tracked down a subtle bug [1] with overriding and
specialization. It's a silent killer: beware!

For those that don't know, specialization was enabled by default in
2.8.0.RC1. You can disable it with the compiler flag:
-no-specialization

-jason

[1] https://lampsvn.epfl.ch/trac/scala/ticket/3434

class F extends Function0[Double] {
def apply: Double = 0.0
}

object G extends F {
override def apply: Double = 1.0
}

val result = (G: F).apply

println(result) // 0.0!