Remove FBREMAP experiment
Remove FBREMAP experiment

Summary:
The flag was removed in https://www.internalfb.com/diff/D28467996 (https://github.com/facebook/react-native/commit/2c5f68df4656b0307e17d86d6e393dee90f2ad2b) but the code was not removed yet.

Changelog: [Internal]

Reviewed By: motiz88

Differential Revision: D33792884

fbshipit-source-id: 0ae5d904ca2ca94437ca63b495d41e47585fde33

facebook/react-native,facebook/react-native,javache/react-native,janicduplessis/react-native,janicduplessis/react-native,facebook/react-native,janicduplessis/react-native,javache/react-native,janicduplessis/react-native,janicduplessis/react-native,javache/react-native,facebook/react-native,facebook/react-native,javache/react-native,facebook/react-native,javache/react-native,janicduplessis/react-native,janicduplessis/react-native,javache/react-native,janicduplessis/react-native,javache/react-native,facebook/react-native,facebook/react-native,javache/react-native,javache/react-native,facebook/react-native