Rollup merge of rust-lang#97308 - JohnTitor:stabilize-cell-filter-map, r=Mark-Simulacrum

Stabilize `cell_filter_map`

FCP has been completed: rust-lang#81061 (comment)
Closes rust-lang#81061

Author: Dylan-DPC

library/core/src/cell.rs

@@ -1390,16 +1390,14 @@ impl<'b, T: ?Sized> Ref<'b, T> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(cell_filter_map)]
-    ///
     /// use std::cell::{RefCell, Ref};
     ///
     /// let c = RefCell::new(vec![1, 2, 3]);
     /// let b1: Ref<Vec<u32>> = c.borrow();
     /// let b2: Result<Ref<u32>, _> = Ref::filter_map(b1, |v| v.get(1));
     /// assert_eq!(*b2.unwrap(), 2);
     /// ```
-    #[unstable(feature = "cell_filter_map", reason = "recently added", issue = "81061")]
+    #[stable(feature = "cell_filter_map", since = "1.63.0")]
     #[inline]
     pub fn filter_map<U: ?Sized, F>(orig: Ref<'b, T>, f: F) -> Result<Ref<'b, U>, Self>
     where
@@ -1538,8 +1536,6 @@ impl<'b, T: ?Sized> RefMut<'b, T> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(cell_filter_map)]
-    ///
     /// use std::cell::{RefCell, RefMut};
     ///
     /// let c = RefCell::new(vec![1, 2, 3]);
@@ -1555,7 +1551,7 @@ impl<'b, T: ?Sized> RefMut<'b, T> {
     ///
     /// assert_eq!(*c.borrow(), vec![1, 4, 3]);
     /// ```
-    #[unstable(feature = "cell_filter_map", reason = "recently added", issue = "81061")]
+    #[stable(feature = "cell_filter_map", since = "1.63.0")]
     #[inline]
     pub fn filter_map<U: ?Sized, F>(mut orig: RefMut<'b, T>, f: F) -> Result<RefMut<'b, U>, Self>
     where