make vecdeque_rotate stable

Author: Dodo

src/liballoc/collections/vec_deque.rs

@@ -1934,8 +1934,6 @@ impl<T> VecDeque<T> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(vecdeque_rotate)]
-    ///
     /// use std::collections::VecDeque;
     ///
     /// let mut buf: VecDeque<_> = (0..10).collect();
@@ -1949,7 +1947,7 @@ impl<T> VecDeque<T> {
     /// }
     /// assert_eq!(buf, [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
     /// ```
-    #[unstable(feature = "vecdeque_rotate", issue = "56686")]
+    #[stable(feature = "vecdeque_rotate", since = "1.35.0")]
     pub fn rotate_left(&mut self, mid: usize) {
         assert!(mid <= self.len());
         let k = self.len() - mid;
@@ -1979,8 +1977,6 @@ impl<T> VecDeque<T> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(vecdeque_rotate)]
-    ///
     /// use std::collections::VecDeque;
     ///
     /// let mut buf: VecDeque<_> = (0..10).collect();
@@ -1994,7 +1990,7 @@ impl<T> VecDeque<T> {
     /// }
     /// assert_eq!(buf, [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
     /// ```
-    #[unstable(feature = "vecdeque_rotate", issue = "56686")]
+    #[stable(feature = "vecdeque_rotate", since = "1.35.0")]
     pub fn rotate_right(&mut self, k: usize) {
         assert!(k <= self.len());
         let mid = self.len() - k;

src/liballoc/tests/lib.rs

@@ -6,7 +6,6 @@
 #![feature(repeat_generic_slice)]
 #![feature(try_reserve)]
 #![feature(unboxed_closures)]
-#![feature(vecdeque_rotate)]
 #![deny(rust_2018_idioms)]
 
 use std::hash::{Hash, Hasher};