Add test

Author: odersky

tests/pos/enums-capture.scala

@@ -0,0 +1,7 @@
+class T
+
+enum Foo[T](val foo: Any) {
+  case Case1(x: Int) extends Foo(new T)
+  case Case2[U](x: U) extends Foo(new T)
+  case Case3 extends Foo(new T)
+}