We should be able to look at see if the child has a data-react-id attribute but isn't rendered by this copy of React and consequently warn.

See https://groups.google.com/forum/#!topic/reactjs/mdwfKKJ0L2Q.

'discouraged, since its children are often manipulated by third-party ' +
      'scripts and browser extensions. This may lead to subtle ' +
      'reconciliation issues. Try rendering into a container element created ' +
      'for your app.'
    );
    var nextWrappedElement = React.createElement(
      TopLevelWrapper,
      { child: nextElement }
    );
    var nextContext;
    if (parentComponent) {
      var parentInst = ReactInstanceMap.get(parentComponent);
      nextContext = parentInst._processChildContext(parentInst._context);
    } else {
      nextContext = emptyObject;
    }
    var prevComponent = getTopLevelWrapperInContainer(container);
    if (prevComponent) {
      var prevWrappedElement = prevComponent._currentElement;
      var prevElement = prevWrappedElement.props.child;
      if (shouldUpdateReactComponent(prevElement, nextElement)) {
        var publicInst = prevComponent._renderedComponent.getPublicInstance();
        var updatedCallback = callback && function() {
          callback.call(publicInst);
        };
        ReactMount._updateRootComponent(
          prevComponent,
          nextWrappedElement,
          nextContext,
          container,