rustdoc: Don't use into_iter() when cleaning impl Trait

Author: Manishearth

src/librustdoc/clean/mod.rs

@@ -2756,7 +2756,7 @@ impl<'tcx> Clean<Type> for Ty<'tcx> {
                 let predicates_of = cx.tcx.predicates_of(def_id);
                 let substs = cx.tcx.lift(&substs).unwrap();
                 let bounds = predicates_of.instantiate(cx.tcx, substs);
-                ImplTrait(bounds.predicates.into_iter().filter_map(|predicate| {
+                ImplTrait(bounds.predicates.iter().filter_map(|predicate| {
                     predicate.to_opt_poly_trait_ref().clean(cx)
                 }).collect())
             }