Revert rust-lang#83357

Author: saethlin

library/alloc/src/raw_vec.rs

@@ -315,24 +315,8 @@ impl<T, A: Allocator> RawVec<T, A> {
     /// #   vector.push_all(&[1, 3, 5, 7, 9]);
     /// # }
     /// ```
-    #[inline]
     pub fn reserve(&mut self, len: usize, additional: usize) {
-        // Callers expect this function to be very cheap when there is already sufficient capacity.
-        // Therefore, we move all the resizing and error-handling logic from grow_amortized and
-        // handle_reserve behind a call, while making sure that the this function is likely to be
-        // inlined as just a comparison and a call if the comparison fails.
-        #[cold]
-        fn do_reserve_and_handle<T, A: Allocator>(
-            slf: &mut RawVec<T, A>,
-            len: usize,
-            additional: usize,
-        ) {
-            handle_reserve(slf.grow_amortized(len, additional));
-        }
-
-        if self.needs_to_grow(len, additional) {
-            do_reserve_and_handle(self, len, additional);
-        }
+        handle_reserve(self.try_reserve(len, additional));
     }
 
     /// The same as `reserve`, but returns on errors instead of panicking or aborting.