Summary:
MeasureLayout requires either a reactTag or a ref to a host component. Now that we have a type for Host Components we can be more differentiating here.
Also, because Object is treated as `any` in flow, the type was allowing the return from findNodeHandle or a ref itself be passed, even though both of those are nullable.
This change explicitly requires checking for null before calling the function which is consistent with the behavior of the implementation of measureLayout.
Changelog:
[Changed] Flowtype for measureLayout now disallows null as reactTag
Reviewed By: cpojer
Differential Revision: D17579300
fbshipit-source-id: af062fcd9dfc40eab42e5c5452af2ff653d0888e
Eli White
bcc58bce02