Summary:
Changes the `ImageURISource` Flow type into an interface.
- This enables both objects and class instances to be subtypes of `ImageURISource`.
- This makes it invalid to spread `ImageURISource` as a type, so `interface X extends ImageURISource` can instead be used.
- This makes it invalid to spread `ImageURISource` as a value, so `getImageSourceProperties(x)` can instead be used.
- This makes it invalid to use `$Exact` with `ImageURISource`.
Changelog:
[General][Changed] - `ImageURISource` Flow type is now an interface instead of an object.
Reviewed By: timrc
Differential Revision: D29323508
fbshipit-source-id: 647c2f9b0bfead6d7e56bdb7108e623cbf8b6c89
Tim Yung
123d184944