Split up createTimer into two methods, createTimer and createTimerFor…

…NextFrame

Summary:
This diff adds nuance to timer creation.  Imagine the following bit of JS:

```
    setTimeout(() => {
      console.log("Timeout")
    }, 0);
    setImmediate(() => {
      setNine("Immediate");
    });
```

In classic RN, `setTimeout` will be called async by the bridge, immediate is implemented in JS, so the ordering of logs will be:

1. Immediate
2. Timeout

In bridgeless RN `setTimeout` is called sync, so the ordering of the logs is:

1. Timeout
2. Immediate

In order to preserve ordering, this diff adds a timer creation method which doesn't immediately invoke it, but waits one frame to do so.

This PR does the same thing for android, and explains the reasoning for preserving behaviour (some products may rely on this behaviour) f054928

Reviewed By: ejanzer

Differential Revision: D17535639

fbshipit-source-id: 3f734c420a6a95be2ee10e8d6ac48adc79ef1c96

React/Modules/RCTTiming.h

@@ -22,10 +22,10 @@
 @interface RCTTiming : NSObject <RCTBridgeModule, RCTInvalidating, RCTFrameUpdateObserver>
 
 - (instancetype)initWithDelegate:(id<RCTTimingDelegate>) delegate;
-- (void)createTimer:(nonnull NSNumber *)callbackID
-           duration:(NSTimeInterval)jsDuration
-   jsSchedulingTime:(NSDate *)jsSchedulingTime
-            repeats:(BOOL)repeats;
+- (void)createTimerForNextFrame:(nonnull NSNumber *)callbackID
+                       duration:(NSTimeInterval)jsDuration
+               jsSchedulingTime:(NSDate *)jsSchedulingTime
+                        repeats:(BOOL)repeats;
 - (void)deleteTimer:(nonnull NSNumber *)timerID;
 
 @end

React/Modules/RCTTiming.m

@@ -351,6 +351,9 @@ - (void)timerDidFire
 }
 
 /**
+ * A method used for asynchronously creating a timer. If the timer has already expired,
+ * (based on the provided jsSchedulingTime) then it will be immediately invoked.
+ *
  * There's a small difference between the time when we call
  * setTimeout/setInterval/requestAnimation frame and the time it actually makes
  * it here. This is important and needs to be taken into account when
@@ -372,6 +375,21 @@ - (void)timerDidFire
     return;
   }
 
+  [self createTimerForNextFrame:callbackID
+                       duration:jsDuration
+               jsSchedulingTime:jsSchedulingTime
+                        repeats:repeats];
+}
+
+/**
+ * A method used for synchronously creating a timer. The timer will not be invoked until the
+ * next frame, regardless of whether it has already expired (i.e. jsSchedulingTime is 0).
+ */
+- (void)createTimerForNextFrame:(nonnull NSNumber *)callbackID
+                       duration:(NSTimeInterval)jsDuration
+               jsSchedulingTime:(NSDate *)jsSchedulingTime
+                        repeats:(BOOL)repeats
+{
   NSTimeInterval jsSchedulingOverhead = MAX(-jsSchedulingTime.timeIntervalSinceNow, 0);
 
   NSTimeInterval targetTime = jsDuration - jsSchedulingOverhead;