LogBox - Deallocate _rootViewController to release surface reference and break cycle
LogBox - Deallocate _rootViewController to release surface reference and break cycle

Summary:
This def breaks a reference cycle in logbox causing a memory leak in development.

Changelog: [iOS] [Fix] LogBox - Fix dependency cycle

Reviewed By: PeteTheHeat

Differential Revision: D19768068

fbshipit-source-id: 518b9c66499aa092465a9213f955965bffeebd88

hoangpham95/react-native,exponent/react-native,hammerandchisel/react-native,myntra/react-native,facebook/react-native,exponent/react-native,arthuralee/react-native,facebook/react-native,pandiaraj44/react-native,exponent/react-native,janicduplessis/react-native,janicduplessis/react-native,janicduplessis/react-native,myntra/react-native,exponentjs/react-native,exponent/react-native,myntra/react-native,hoangpham95/react-native,janicduplessis/react-native,janicduplessis/react-native,hammerandchisel/react-native,exponentjs/react-native,pandiaraj44/react-native,pandiaraj44/react-native,exponentjs/react-native,arthuralee/react-native,pandiaraj44/react-native,javache/react-native,hammerandchisel/react-native,pandiaraj44/react-native,exponentjs/react-native,hoangpham95/react-native,pandiaraj44/react-native,exponentjs/react-native,arthuralee/react-native,arthuralee/react-native,myntra/react-native,javache/react-native,exponentjs/react-native,javache/react-native,hammerandchisel/react-native,myntra/react-native,hoangpham95/react-native,pandiaraj44/react-native,facebook/react-native,javache/react-native,exponent/react-native,myntra/react-native,myntra/react-native,facebook/react-native,pandiaraj44/react-native,facebook/react-native,javache/react-native,myntra/react-native,exponent/react-native,janicduplessis/react-native,facebook/react-native,janicduplessis/react-native,javache/react-native,arthuralee/react-native,myntra/react-native,javache/react-native,hammerandchisel/react-native,facebook/react-native,exponentjs/react-native,exponent/react-native,hammerandchisel/react-native,hoangpham95/react-native,hammerandchisel/react-native,hoangpham95/react-native,exponent/react-native,javache/react-native,facebook/react-native,facebook/react-native,exponentjs/react-native,javache/react-native,hammerandchisel/react-native,hoangpham95/react-native,janicduplessis/react-native,hoangpham95/react-native