Replaced "window" references with "global"

Author: Brian Vaughn

src/renderers/native/ReactNativeFiber.js

@@ -294,9 +294,9 @@ const NativeRenderer = ReactFiberReconciler({
     // Noop?
   },
 
-  scheduleAnimationCallback: window.requestAnimationFrame,
+  scheduleAnimationCallback: global.requestAnimationFrame,
 
-  scheduleDeferredCallback: window.requestIdleCallback,
+  scheduleDeferredCallback: global.requestIdleCallback,
 
   shouldSetTextContent(props : Props) : boolean {
     return false;