stabilize hash_map_remove_entry feature

Author: tinaun

src/libstd/collections/hash/map.rs

@@ -1379,7 +1379,6 @@ impl<K, V, S> HashMap<K, V, S>
     /// # Examples
     ///
     /// ```
-    /// #![feature(hash_map_remove_entry)]
     /// use std::collections::HashMap;
     ///
     /// # fn main() {
@@ -1389,7 +1388,7 @@ impl<K, V, S> HashMap<K, V, S>
     /// assert_eq!(map.remove(&1), None);
     /// # }
     /// ```
-    #[unstable(feature = "hash_map_remove_entry", issue = "46344")]
+    #[stable(feature = "hash_map_remove_entry", since = "1.27.0")]
     pub fn remove_entry<Q: ?Sized>(&mut self, k: &Q) -> Option<(K, V)>
         where K: Borrow<Q>,
               Q: Hash + Eq