Is this a bug report?

yes

Have you read the Contributing Guidelines?

Yes

Environment

Environment:
OS: macOS Sierra 10.12.6
Node: 8.4.0
Yarn: Not Found
npm: 5.3.0
Watchman: 4.5.0
Xcode: Xcode 9.0 Build version 9A235
Android Studio: Not Found

Packages:
  react: 16.0.0-alpha.12
  react-native: 0.47.2

Target Platform: iOS (10.3)

Steps to Reproduce

(Write your steps here:)

1. Create new project
2. Save a gif with camera roll. CameraRoll.saveToCameraRoll('https://k60.kn3.net/B/1/5/9/2/D/971.gif');

Expected Behavior

The gif should be animated.

Actual Behavior

The gif was saved in photo album but is an static image. It hasn't got animation and only the first frame is shown.
Maybe is related with #16117

Reproducible Demo

Here is an example code to reproduce. But snack does not allow to see the images of the device. I think.
https://snack.expo.io/BkAe8yE2Z