Fix: add check that Java value class type conforms

Author: alexander-myltsev

tests/run/classof.scala

@@ -5,6 +5,7 @@ object Test {
   def main(args: Array[String]): Unit = {
     val cls: Predef.Class[SomeClass] = classOf[SomeClass]
     val valCls: Predef.Class[ValueClass] = classOf[ValueClass]
+    val iCls: Class[Int] = classOf[Int]
 
     println("Value types:")
     println(classOf[Unit])