auto merge of #7008 : thestinger/rust/iterator, r=catamorphism

The `IteratorUtil` trait hits a bug in method resolve, but the basic trait has no issue.

Author: bors

src/libstd/prelude.rs

@@ -51,6 +51,7 @@ pub use old_iter::{CopyableIter, CopyableOrderedIter, CopyableNonstrictIter};
 pub use old_iter::{ExtendedMutableIter};
 pub use iter::{Times, FromIter};
 // FIXME: #5898 pub use iterator::{Iterator, IteratorUtil};
+pub use iterator::Iterator;
 pub use num::{Num, NumCast};
 pub use num::{Orderable, Signed, Unsigned, Round};
 pub use num::{Algebraic, Trigonometric, Exponential, Hyperbolic};