completeUnitOfWork: 失去要更新的 Fiber，造成链表

params

  1. unitOfWork

代码

if (returnFiber !== null && (returnFiber.flags & Incomplete) === NoFlags) {  if (returnFiber.firstEffect === null) {    returnFiber.firstEffect = completedWork.firstEffect;  }  if (completedWork.lastEffect !== null) {    if (returnFiber.lastEffect !== null) {      returnFiber.lastEffect.nextEffect = completedWork.firstEffect;    }    returnFiber.lastEffect = completedWork.lastEffect;  }  var flags = completedWork.flags;  if (flags > PerformedWork) {    if (returnFiber.lastEffect !== null) {      returnFiber.lastEffect.nextEffect = completedWork;    } else {      returnFiber.firstEffect = completedWork;    }    returnFiber.lastEffect = completedWork;  }}