Add lifetime to FutureObj

src/libcore/task/mod.rs

@@ -25,8 +25,5 @@ pub use self::executor::{
 mod poll;
 pub use self::poll::Poll;
 
-mod future_obj;
-pub use self::future_obj::{FutureObj, LocalFutureObj, UnsafeFutureObj};
-
 mod wake;
 pub use self::wake::{Waker, LocalWaker, UnsafeWake};