Remove stabilized feature gates.

These are:

  * i128_type
  * conservative_impl_trait
  * never_type

codegen/src/lib.rs

@@ -1,8 +1,6 @@
 #![crate_type = "dylib"]
 #![feature(quote, concat_idents, plugin_registrar, rustc_private)]
-#![feature(iterator_for_each)]
 #![feature(custom_attribute)]
-#![feature(i128_type)]
 #![allow(unused_attributes)]
 #![allow(deprecated)]
 

contrib/src/lib.rs

@@ -1,5 +1,4 @@
 #![feature(macro_reexport)]
-#![cfg_attr(feature = "templates", feature(conservative_impl_trait))]
 
 // TODO: Version URLs.
 #![doc(html_root_url = "https://api.rocket.rs")]

lib/src/lib.rs

@@ -1,8 +1,6 @@
 #![feature(specialization)]
-#![feature(conservative_impl_trait)]
 #![feature(const_fn)]
 #![feature(plugin, decl_macro)]
-#![feature(never_type)]
 #![feature(try_trait)]
 #![recursion_limit="256"]