Remove unreachable code (#13762)

packages/react-reconciler/src/ReactFiberScheduler.js

@@ -929,23 +929,12 @@ function completeUnitOfWork(workInProgress: Fiber): Fiber | null {
           nextRenderExpirationTime,
         );
       }
-      let next = nextUnitOfWork;
       stopWorkTimer(workInProgress);
       resetChildExpirationTime(workInProgress, nextRenderExpirationTime);
       if (__DEV__) {
         ReactCurrentFiber.resetCurrentFiber();
       }
 
-      if (next !== null) {
-        stopWorkTimer(workInProgress);
-        if (__DEV__ && ReactFiberInstrumentation.debugTool) {
-          ReactFiberInstrumentation.debugTool.onCompleteWork(workInProgress);
-        }
-        // If completing this work spawned new work, do that next. We'll come
-        // back here again.
-        return next;
-      }
-
       if (
         returnFiber !== null &&
         // Do not append effects to parents if a sibling failed to complete