Fix copy_iterator uitest

Author: mgacek8

tests/ui/copy_iterator.rs

@@ -16,8 +16,6 @@ impl Iterator for Countdown {
 
 fn main() {
     let my_iterator = Countdown(5);
-    let a: Vec<_> = my_iterator.take(1).collect();
-    assert_eq!(a.len(), 1);
-    let b: Vec<_> = my_iterator.collect();
-    assert_eq!(b.len(), 5);
+    assert_eq!(my_iterator.take(1).count(), 1);
+    assert_eq!(my_iterator.count(), 5);
 }