message: Iterate over .keys() instead of the entire map
  Appeases the clippy::for_kv_map lint.
diff: @@ -121,7 +121,7 @@ impl VertexAttributesSystem {
  let mut vaos = ctxt.vertex_array_objects.vaos.borrow_mut();
  let mut keys = Vec::with_capacity(4);
  - for (key, _) in &*vaos {
  + for key in (*vaos).keys() {
  if condition(key) {
  keys.push(key.clone());
  }
  