Summary:
Changes `ExceptionsManager` in React Native so that errors with a `type` property equal to `'warn'` are not reported.
This change is banking on the fact that `type` is a non-standard and uncommon property on `Error` instances. If this ends up being problematic, we can instead change this to use a `unstable_type` or `unstable_level` property instead.
Changelog:
[General][Changed] - ExceptionsManager will no longer report exceptions with `type === 'warn'`.
Reviewed By: motiz88
Differential Revision: D28421692
fbshipit-source-id: 3ca19e29f32c8c5cad6dac637dcb930944fb24ed