- `ASDisplayNode` can be told to not flatten its layout immediately but later on. The unflattened layout is also stored in a separate property. It's needed for inspecting not only display nodes but also layout specs used to compute a layout tree.
- `ASLayout` can be told to always retain its sublayout elements. This is needed especially for layout specs since they are usually not retained after an ASLayout was computed.
It is rare that this code has any effect, but I've discovered a case in which it occurs.
This task tracks moving this code to a DEBUG-only assertion: https://github.com/TextureGroup/Texture/issues/335