Adapt test: use class instead of type params

Author: liufengyun

tests/patmat/i8690b.scala

@@ -1,4 +1,7 @@
-def test[A, B](x: (A, B) | (B, A)) = x match {
+class A
+class B
+
+def test(x: (A, B) | (B, A)) = x match {
   case (u: A, v: B) => (u, v)
   case (u: B, v: A) => (v, u)
 }