`call` method on a pointer to an implentation of `RecurFn` mistakenly calls `dyn_body` instead of `body`.#1

Let's say, we have a Box of a `RecurFn` implementation. ```rust let a = Box::new(recur_fn(|fib, n: u64| -> u64 { if n <= 1 { 1 } else { fib(n-1) + fib(n-2) } })); ``` When evaluating `a.call(3)`, it will first lookup the implementation of `RecurFn` for `Box<impl RecurFn>`, which goes to ```rust impl<Arg, Output, D: Deref> RecurFn<Arg, Output> for D where D::Target: DynRecurFn<Arg, Output>, ``` and it's `call` method goes to `dyn_body`. But what we want is to use `body` method.