Add lost test from tests/neg-custom-args/no-experimental/experimental.scala

Author: nicolasstucki

tests/neg-custom-args/no-experimental/experimental-2.scala

@@ -0,0 +1,5 @@
+class Test7 {
+  import scala.language.experimental
+  import experimental.genericNumberLiterals // error: no aliases can be used to refer to a language import
+  val x: BigInt = 13232202002020202020202   // error
+}

tests/neg-custom-args/no-experimental/experimental.scala

@@ -25,4 +25,4 @@ class Test2 {
 
 class Test6 {
   import scala.language.experimental  // ok
-}
+}