Animated module: don't use random IDs as waiting identifier for queueing

Summary:
In D24521951 (2ff1d4c041) I refactored the JS-side queueing for NativeAnimated API calls, and used randomized IDs for queueing. This could cause bugs or unexpected behavior, and potentially crashes, if there's ever a collision in random numbers generated or
a collision between random number and one of the deterministic numbers generated in createAnimatedComponent.

In this diff I make both of them namespaced with a string, and deterministic, to eliminate any potential collisions. This could also be slightly faster (but not meaningfully) since we're not relying on Math.random.

Changelog: [Internal]

Reviewed By: yungsters

Differential Revision: D24553557

fbshipit-source-id: 8b765e21597ad4f8e641453c1f9f90bdf1ee022f

Libraries/Animated/NativeAnimatedHelper.js

@@ -53,11 +53,11 @@ const API = {
       NativeAnimatedModule.getValue(tag, saveValueCallback);
     }
   },
-  setWaitingForIdentifier: function(id: number): void {
+  setWaitingForIdentifier: function(id: string): void {
     waitingForQueuedOperations.add(id);
     queueOperations = true;
   },
-  unsetWaitingForIdentifier: function(id: number): void {
+  unsetWaitingForIdentifier: function(id: string): void {
     waitingForQueuedOperations.delete(id);
 
     if (waitingForQueuedOperations.size === 0) {

Libraries/Animated/animations/Animation.js

@@ -24,6 +24,8 @@ export type AnimationConfig = {
   iterations?: number,
 };
 
+let startNativeAnimationNextId = 1;
+
 // Important note: start() and stop() will only be called at most once.
 // Once an animation has been stopped or finished its course, it will
 // not be reused.
@@ -57,8 +59,11 @@ class Animation {
     onEnd && onEnd(result);
   }
   __startNativeAnimation(animatedValue: AnimatedValue): void {
-    const arbitraryValue = Math.random();
+    const startNativeAnimationWaitId = `${startNativeAnimationNextId}:startAnimation`;
-    NativeAnimatedHelper.API.setWaitingForIdentifier(arbitraryValue);
+    startNativeAnimationNextId += 1;
+    NativeAnimatedHelper.API.setWaitingForIdentifier(
+      startNativeAnimationWaitId,
+    );
     try {
       animatedValue.__makeNative();
       this.__nativeId = NativeAnimatedHelper.generateNewAnimationId();
@@ -71,7 +76,9 @@ class Animation {
     } catch (e) {
       throw e;
     } finally {
-      NativeAnimatedHelper.API.unsetWaitingForIdentifier(arbitraryValue);
+      NativeAnimatedHelper.API.unsetWaitingForIdentifier(
+        startNativeAnimationWaitId,
+      );
     }
   }
 }

Libraries/Animated/createAnimatedComponent.js

@@ -55,7 +55,7 @@ function createAnimatedComponent<Props: {+[string]: mixed, ...}, Instance>(
     _eventDetachers: Array<Function> = [];
 
     // Only to be used in this file, and only in Fabric.
-    _animatedComponentId: number = animatedComponentNextId++;
+    _animatedComponentId: string = `${animatedComponentNextId++}:animatedComponent`;
 
     _attachNativeEvents() {
       // Make sure to get the scrollable node for components that implement