Summary:
Due to the changes in 46817a38. We have a bug if the layout changes.
This PR fixes this bug and adds a test for it.
Additionally it correctly marks negative percentage values as undefined dim.
It also changes the ```resolvedDimensions``` to use a reference instead of the full value in order to minimize the memory requirement of a ```YGNode``` and reduces the copying of the ```YGValue```.
Closes https://github.com/facebook/yoga/pull/379
Reviewed By: gkassabli
Differential Revision: D4528552
Pulled By: emilsjolander
fbshipit-source-id: c024fe3a009c3788af319b689858ea3374c46477