Add xfail'd test for a default method containing 'self'.

Author: lkuper

src/test/run-pass/traits-default-method-self.rs

@@ -0,0 +1,21 @@
+//xfail-test
+
+// Right now, this fails with "attempted access of field `purr` on
+// type `self`, but no public field or method with that name was
+// found".
+
+trait Cat {
+    fn meow() -> bool;
+    fn scratch() -> bool { self.purr() }
+    fn purr() -> bool { true }
+}
+
+impl int : Cat {
+    fn meow() -> bool {
+        self.scratch()
+    }
+}
+
+fn main() {
+    assert 5.meow();
+}