Add test for #9971

Author: nicolasstucki

tests/neg/i9971.check

@@ -0,0 +1,5 @@
+-- [E007] Type Mismatch Error: tests/neg/i9971.scala:6:10 --------------------------------------------------------------
+6 |def b = f(a) // error
+  |          ^
+  |          Found:    G[[A <: Int] =>> List[A]]
+  |          Required: G[List]

tests/neg/i9971.scala

@@ -0,0 +1,6 @@
+trait G[F[_]]
+
+def f(x: G[List]) = ???
+
+def a: G[[A <: Int] =>> List[A]] = ???
+def b = f(a) // error