This usually means that the user mixed up our lowercase/uppercase naming convention; see https://github.com/facebook/react/pull/3429#issuecomment-85166440.

We could add a message like

> Warning: The tag <commentBox> is unrecognized in this browser. If you meant to render a React component, start its name with an uppercase letter.

We'd check this only once per tag and only in development mode.

this._hostParent = hostParent;
    this._hostContainerInfo = hostContainerInfo;
    var props = this._currentElement.props;
    switch (this._tag) {
      case 'audio':
      case 'form':
      case 'iframe':
      case 'img':
      case 'image':
      case 'link':
      case 'object':
      case 'source':
      case 'video':
      case 'details':
        this._wrapperState = {
          listeners: null,
        };
        transaction.getReactMountReady().enqueue(trapBubbledEventsLocal, this);
        break;
      case 'input':
        ReactDOMInput.mountWrapper(this, props, hostParent);
        props = ReactDOMInput.getHostProps(this, props);
        transaction.getReactMountReady().enqueue(trackInputValue, this);
        transaction.getReactMountReady().enqueue(trapBubbledEventsLocal, this);
        
        
        ensureListeningTo(this, 'onChange', transaction);
        break;
      case 'option':
        ReactDOMOption.mountWrapper(this, props, hostParent);