6639ed3b3a
While inspecting the build artifacts for Fabric in https://www.internalfb.com/diff/D51816108, I've noticed it has some leaking implementation details from Paper, such as `ReactNativeFiberHostComponent`. The reason for it is the single implementation of `isChildPublicInstance` in `ReactNativePublicCompat`, in which we were using `instanceof ReactNativeFiberHostComponent`. This new implementation removes the `ReactNativeFiberHostComponent` leak, but decreases the Flow coverage.