Summary:
When a non-leaf node becomes a leaf node, `YGAttachNodesFromViewHierachy` calls `YGNodeSetMeasureFunc` before `YGRemoveAllChildren`, which causes a crash because that node has children. Fixed by swapping the order of the calls and have a unit-test to make sure it works.
Closes https://github.com/facebook/yoga/pull/320
Differential Revision: D4383905
Pulled By: dshahidehpour
fbshipit-source-id: 4872b1e819f178adaaa66b1f1c233390d3ec3be9
1877a97898