Added MobileConfig for ReactNative use-fiber

Reviewed By: yungsters

Differential Revision: D4740267

fbshipit-source-id: d2cf76a22ce0f6337e1055b9f4b869c8bd82fa7d

Libraries/Renderer/src/renderers/native/ReactNativeFeatureFlags.js

@@ -7,6 +7,7 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  *
  * @providesModule ReactNativeFeatureFlags
+ * @flow
  */
 
 'use strict';