Different semantics for `Double.NaN` between Scala2 and Dotty

[liufengyun]

minimized code

Dotty REPL:

scala> Double.NaN > 0.0
val res1: Boolean = true
scala> Float.NaN > 0.0
val res2: Boolean = true
scala> Float.NaN < 0.0
val res3: Boolean = true
scala> Double.NaN < 0.0
val res4: Boolean = true

expectation

Should return false, as in Scala REPL:

scala> Double.NaN > 0.0
res1: Boolean = false
scala> Float.NaN > 0.0
val res2: Boolean = false
scala> Float.NaN < 0.0
val res3: Boolean = false
scala> Double.NaN < 0.0
val res4: Boolean = false

This is discovered when working with ScalaTest test set.