Update result.rs

Remove a FIXME whose code got moved away in rust-lang#62883.

Author: hkBst

library/core/src/result.rs

@@ -2066,9 +2066,6 @@ impl<A, E, V: FromIterator<A>> FromIterator<Result<A, E>> for Result<V, E> {
     /// so the final value of `shared` is 6 (= `3 + 2 + 1`), not 16.
     #[inline]
     fn from_iter<I: IntoIterator<Item = Result<A, E>>>(iter: I) -> Result<V, E> {
-        // FIXME(#11084): This could be replaced with Iterator::scan when this
-        // performance bug is closed.
-
         iter::try_process(iter.into_iter(), |i| i.collect())
     }
 }