Summary: The memory leaks root from the TabBarController not removing itself
when its holder view deallocs. So to fix the issue, it’s just to remove
it from its parentViewController when the holding RCTTabBar
deallocs. This should be safe, since the RCTTabBar seems the owner
of the TabBarController.
Closes https://github.com/facebook/react-native/pull/3915
Reviewed By: svcscm
Differential Revision: D2620905
Pulled By: nicklockwood
fb-gh-sync-id: ce22eb3ebf82562827f6b1bae22aea5ac7d3b51a
d8dd330d41