Summary:
When building a native component which takes an image reference as a prop, `resolveAssetSource` needs to be called on the image reference. If this isn't done, the native component may receive the opaque type returned by `require` (e.g. `require('./foo.png')`) which is useless to the native component. `resolveAssetSource` is used by builtin components that take image references such as `Image`, `WebView` and `MapView`.
This change makes `resolveAssetSource` public so that third-party native components can correctly handle image references.
**Test plan (required)**
Verified that `Image.resolveAssetSource` works in a test app. Also, my team is using this change in our app.
Adam Comella
Microsoft Corp.
Closes https://github.com/facebook/react-native/pull/10904
Differential Revision: D4177803
Pulled By: ericvicenti
fbshipit-source-id: ffc511b9340325f7d1111002309cd8558ab8e6b0
fde7c35449