std: Remove unused attributes

This also enables two tests properly.

src/libstd/cell.rs

@@ -10,8 +10,6 @@
 
 //! Types dealing with dynamic mutability
 
-#[missing_doc];
-
 use prelude::*;
 use cast;
 use util::NonCopyable;

src/libstd/vec.rs

@@ -2704,7 +2704,7 @@ fn test_init() {
         assert_eq!(a.init(), &[11]);
     }
 
-    #[init]
+    #[test]
     #[should_fail]
     fn test_init_empty() {
         let a: ~[int] = ~[];
@@ -2719,7 +2719,7 @@ fn test_initn() {
         assert_eq!(a.initn(2), &[11]);
     }
 
-    #[init]
+    #[test]
     #[should_fail]
     fn test_initn_empty() {
         let a: ~[int] = ~[];

src/test/run-pass/ifmt.rs

@@ -23,7 +23,6 @@
 struct A;
 struct B;
 
-#[fmt="foo"]
 impl fmt::Signed for A {
     fn fmt(_: &A, f: &mut fmt::Formatter) { f.buf.write("aloha".as_bytes()); }
 }