Summary:
`enum class` types do not provide default conversion to integers and reguire use typename before value names.
This must prevent bugs like the previous one where we used `Undefined` as a number value.
Reviewed By: fkgozali
Differential Revision: D7554548
fbshipit-source-id: b19379aae48c9aebe03043e08cf3acc712da3cb8
Summary: LayoutableShadowNode defines a unified interface (and set of primitives) essential for laying out shadow nodes.
Reviewed By: fkgozali
Differential Revision: D7230668
fbshipit-source-id: d8c1772d4c3bd1f87c41f7240a39aecebf3696ae