Enable test for rust-lang#3707

Author: brson

src/test/compile-fail/issue-3707.rs

@@ -8,7 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// xfail-test
 struct Obj {
     member: uint
 }
@@ -17,8 +16,8 @@ pub impl Obj {
     fn boom() -> bool {
         return 1+1 == 2
     }
-    fn chirp() {
-        self.boom(); //~ ERROR wat
+    fn chirp(&self) {
+        self.boom(); //~ ERROR `&Obj` does not implement any method in scope named `boom`
     }
 }