Summary:
Motivation:
Few days ago gaearon [filed an issue](https://github.com/facebook/react-native/issues/12406) that examples in the react-native repo doesn't work after the [recent changes in local-cli](bce6ece5f6). This PR fixes reported bug.
**Test plan (required)**
- No UI changes
- [x] Run UIExplorer from XCode (no package.json in the folder) and check if packager/application runs correctly
cc davidaurelio satya164 grabbou
Closes https://github.com/facebook/react-native/pull/12435
Differential Revision: D4657370
Pulled By: ericvicenti
fbshipit-source-id: 72ee4b96cae37c7ed2794ed4490ce7b4fbbd66c3