Summary:
This PR provides a workaround for issue #9605 which affects projects which directly or indirectly require `whatwg-fetch`. At that point, all symbolication on stack trace errors fails due to a circular require caused by RN's lazy loading of `fetch`, which results in `fetch` becoming `undefined`.
The workaround is simple: we postpone requiring `fetch` until the first `symbolicateStackTrace` call, at which point we can be certain `fetch` is properly exported. It is then cached for future use.
No tests have been added since, apparently, this module did not have any tests to begin with. Manual tests were performed on a regular project (not including `whatwg-fetch` externally) and a project that has direct and indirect includes for `whatwg-fetch`.
Closes https://github.com/facebook/react-native/pull/10247
Differential Revision: D4175835
Pulled By: hramos
fbshipit-source-id: d849a5874373e76f166ea6ab23f0f888792d1aef
be5e300abf