- It is entirely derived from `SkinLayoutInfo.DrawableInfo`, which is
the actual primary thing we want to serialise.
- It will never get read out from any serialised files anyway (corollary
of the previous point - it is a get-only property derived from another).
- It is only used in tests.
All of the three reasons above make serialising the property out to skin
files nothing more than a waste of space.
Functionally equivalent right now, but the combined variant is more
localised to what it actually needs to do, and less error-prone if
any new code gets appended to the method.
Reproduction scenario:
1. Hover a toolbox item
2. Unhover the item, but do not hover any other item (can be done by
exiting the toolbox completely to the right)
3. Come back to the item hovered in step (1)
4. The item would spontaneously contract after a second