Remove uneeded feature gates

Author: phil-opp

src/lib.rs

@@ -35,14 +35,9 @@
 #![cfg_attr(feature = "unstable", feature(core_intrinsics))]
 #![cfg_attr(feature = "unstable", feature(slice_range))]
 #![cfg_attr(feature = "unstable", feature(slice_ptr_get))]
-#![cfg_attr(feature = "unstable", feature(slice_ptr_len))]
-#![cfg_attr(feature = "very_unstable", feature(const_slice_ptr_len))]
 #![cfg_attr(feature = "very_unstable", feature(const_trait_impl))]
-#![cfg_attr(feature = "very_unstable", feature(const_mut_refs))]
-#![cfg_attr(feature = "very_unstable", feature(inline_const))]
 #![cfg_attr(feature = "very_unstable", feature(unboxed_closures))]
 #![cfg_attr(feature = "very_unstable", feature(fn_traits))]
-#![cfg_attr(all(feature = "unstable", test), feature(slice_as_chunks))]
 #![warn(missing_docs)]
 #![deny(unsafe_op_in_unsafe_fn)]