Add test case for #3264

Author: allanrenucci

tests/pos/i3264.scala

@@ -0,0 +1,15 @@
+trait Foo[+F[_]] {
+  def bar: Bar[F]
+}
+
+trait Bar[+F[_]]
+
+trait Base[+A]
+trait Sub[A] extends Base[A]
+
+class Test {
+  def makeFoo(barSub: Bar[Sub]): Foo[Base] =
+    new Foo[Base] {
+      def bar/*: Bar[Base]*/ = barSub
+    }
+}