We don't actually use this anywhere, so let's remove it.

https://github.com/facebook/react/blob/f1d00156df5453bc62bd5668fefdcac4ca67e90e/src/renderers/shared/fiber/ReactFiberScheduler.js#L1504-L1512
isBatchingUpdates = previousIsBatchingUpdates;
      priorityContext = previousPriorityContext;
      invariant(
        !isPerformingWork,
        'flushSync was called from inside a lifecycle method. It cannot be ' +
          'called when React is already rendering.',
      );
      performWork(TaskPriority, null);
    }
  }
  function deferredUpdates<A>(fn: () => A): A {
    const previousPriorityContext = priorityContext;
    priorityContext = LowPriority;
    try {
      return fn();
    } finally {
      priorityContext = previousPriorityContext;
    }
  }
  return {
    scheduleUpdate: scheduleUpdate,
    getPriorityContext: getPriorityContext,
    performWithPriority: performWithPriority,
    batchedUpdates: batchedUpdates,
    unbatchedUpdates: unbatchedUpdates,
    flushSync: flushSync,
    deferredUpdates: deferredUpdates,
  };
};