Reduce and prevent unnecessary random-access to `List`

Random-access access to `List` when iterating is `O(n^2)` (`O(n)` when
accessing a single element)

* Removed subscript operator, in favor of a more explicit `get`
* Added conversion from `Iterator` to `ConstIterator`
* Remade existing operations into other solutions when applicable

1 files changed, 3 insertions, 3 deletions

diff --git a/scene/animation/animation_tree.cpp b/scene/animation/animation_tree.cpp
index 4880a0f6ed..28a163768f 100644
--- a/scene/animation/animation_tree.cpp
+++ b/scene/animation/animation_tree.cpp
@@ -854,10 +854,10 @@ void AnimationTree::_setup_animation_player() {
 		}
 		List<StringName> list;
 		player->get_animation_library_list(&list);
-		for (int i = 0; i < list.size(); i++) {
-			Ref<AnimationLibrary> lib = player->get_animation_library(list[i]);
+		for (const StringName &E : list) {
+			Ref<AnimationLibrary> lib = player->get_animation_library(E);
 			if (lib.is_valid()) {
-				add_animation_library(list[i], lib);
+				add_animation_library(E, lib);
 			}
 		}
 	}