try to fix loader test with clumsy iteration reversal

core/src/loader.rs

@@ -355,15 +355,17 @@ impl<'gc> LoadManager<'gc> {
     ///
     /// This also removes all movie loaders that have completed.
     pub fn movie_clip_on_load(&mut self, queue: &mut ActionQueue<'gc>) {
-        let mut invalidated_loaders = vec![];
+        let mut loaders: Vec<_> = self.0.keys().collect();
+        loaders.reverse();
 
-        for (index, loader) in self.0.iter_mut() {
-            if loader.movie_clip_loaded(queue) {
-                invalidated_loaders.push(index);
-            }
-        }
+        loaders.retain(|handle| {
+            self.0
+                .get_mut(*handle)
+                .expect("valid key")
+                .movie_clip_loaded(queue)
+        });
 
-        for index in invalidated_loaders {
+        for index in loaders {
             self.0.remove(index);
         }
     }