Opaque types don't seem to support strictEquality

[SethTisue]

with 0.11.0-RC1, this prints true:

import language.strictEquality

object O {

  opaque type Meters = Double
  object Meters { def apply(d: Double): Meters = d }
  implicit def eqM: Eq[Meters, Meters] = Eq

  opaque type Feet = Double
  object Feet { def apply(d: Double): Feet = d }
  implicit def eqF: Eq[Feet, Feet] = Eq

  def main(args: Array[String]): Unit =
    println(Feet(3) == Meters(3))

}

I'd hoped for a compile error ("Values of types Feet and Meters cannot be compared with == or !=")

happens in the REPL too, without the object wrapper, but I made this version too to make sure it wasn't a REPL artifact.

/cc @tpolecat