Summary:
First, LayoutableShadowNode::cloneAndReplaceChild() is now pure virtual. The default implementation was useless and confusing.
Second, cloneAndReplaceChild() is now fully implemented for ViewShadowNode, so fancy Yoga Concurrent layout *should* work now.
Reviewed By: mdvacca
Differential Revision: D7376352
fbshipit-source-id: 1199a37e64535c8592a2a5480e60139f61d02006