This version enables [struct field reordering][1] which brings the size
of the types for specified values of some CSS properties under the threshold
such that they shouldn’t be boxed anymore, making unit tests fail.
Simply unboxing them moves the test failure to Stylo’s unit tests,
since the stable compiler used in that case does not do field re-ordering.
Therefore, we manually reorder a couple fields to effectively bring this
optimization to older compilers for a few specific types.
[1]: https://github.com/rust-lang/rust/pull/40377
