**Do you want to request a *feature* or report a *bug*?**
Bug

**What is the current behavior?**
Page load throws console error: `Warning: Stateless function components cannot be given refs. Attempts to access this ref will fail.null`

```
// Chrome console
6VM598:27 Warning: Stateless function components cannot be given refs. Attempts to access this ref will fail.null
window.console.error @ VM598:27
printWarning @ warning.js:36
warning @ warning.js:60
mountIndeterminateComponent @ react-dom.development.js:10488
beginWork @ react-dom.development.js:10647
performUnitOfWork @ react-dom.development.js:12621
workLoop @ react-dom.development.js:12730
callCallback @ react-dom.development.js:1319
invokeGuardedCallbackDev @ react-dom.development.js:1358
invokeGuardedCallback @ react-dom.development.js:1215
performWork @ react-dom.development.js:12848
batchedUpdates @ react-dom.development.js:13292
performFiberBatchedUpdates @ react-dom.development.js:1666
stackBatchedUpdates @ react-dom.development.js:1657
batchedUpdates @ react-dom.development.js:1671
batchedUpdatesWithControlledComponents @ react-dom.development.js:1684
dispatchEvent @ react-dom.development.js:1894
```

**What is the expected behavior?**
No console error. Or at least some way to trace which is the stateless component that is causing the issue.

**Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?**
`"react": "^16.0.0-rc.3",`
`Chrome Version 60.0.3112.113 (Official Build) (64-bit)`
`macOS Sierra 10.12.6`


- This error only started to appear after upgrading from React 15 -> 16.
return null;
  }
  function performUnitOfWork(workInProgress: Fiber): Fiber | null {
    
    
    
    
    const current = workInProgress.alternate;
    
    if (__DEV__) {
      startWorkTimer(workInProgress);
    }
    let next = beginWork(current, workInProgress, nextPriorityLevel);
    if (__DEV__ && ReactFiberInstrumentation.debugTool) {
      ReactFiberInstrumentation.debugTool.onBeginWork(workInProgress);
    }
    if (next === null) {
      
      next = completeUnitOfWork(workInProgress);
    }
    ReactCurrentOwner.current = null;
    if (__DEV__) {
      ReactDebugCurrentFiber.resetCurrentFiber();
    }
    return next;
  }
  function performFailedUnitOfWork(workInProgress: Fiber): Fiber | null {