Un-xfail tests.

src/test/run-pass/anon-obj-overriding-reduced.rs

-//xfail-stage0
-
 // Reduced test case for issue #543.
 fn main() {
 

src/test/run-pass/anon-obj-overriding.rs

-//xfail-stage0
-
 use std;
 
 fn main() {

src/test/run-pass/anon-obj-with-self-call-2.rs

-//xfail-stage0
-
 // Reduced test case for issue #540.
 fn main() {
     obj a() {

src/test/run-pass/anon-obj-with-self-call.rs

-//xfail-stage0
-
 use std;
 
 fn main() {