Add test case

Author: odersky

Diff for: tests/pos/orinf.scala

@@ -0,0 +1,6 @@
+object Test {
+
+  def foo(lis: scala.collection.immutable.Set[Int] | scala.collection.immutable.Set[String]) = lis
+  foo(Set(1))
+  foo(Set(""))
+}