Fix bug computing typeParams for hk types

Arg bounds do not count is bindings.
Also: TypeLambda's $Apply binding should be covariant,
because the parameter is (not sure it matters though).

Author: odersky

src/dotty/tools/dotc/core/TypeApplications.scala

@@ -57,7 +57,7 @@ object TypeApplications {
       assert(argBoundss.length == variances.length)
       RefinedType(
         argRefinements(defn.LambdaTrait(variances).typeRef, 0, argBoundss),
-        tpnme.hkApply, rt => bodyFn(rt).bounds)
+        tpnme.hkApply, rt => TypeAlias(bodyFn(rt), 1))
     }
 
     def unapply(tp: Type)(implicit ctx: Context): Option[(List[Int], List[TypeBounds], Type)] = tp match {

src/dotty/tools/dotc/core/Types.scala

@@ -1929,7 +1929,7 @@ object Types {
         false
     }
     override def computeHash = doHash(refinedName, refinedInfo, parent)
-    override def toString = s"RefinedType($parent, $refinedName, $refinedInfo | $hashCode)" // !!! TODO: remove
+    override def toString = s"RefinedType($parent, $refinedName, $refinedInfo)"
   }
 
   class CachedRefinedType(parent: Type, refinedName: Name, infoFn: RefinedType => Type) extends RefinedType(parent, refinedName) {