function hasNonRootReactChild(container) {
  var rootEl = getReactRootElementInContainer(container);
  if (rootEl) {
    var inst = ReactDOMComponentTree.getInstanceFromNode(rootEl);
    return !!(inst && inst._hostParent);
  }
}
Take a component that's already mounted into the DOM and replace its props
@param {ReactComponent} prevComponent component instance already in the DOM
@param {ReactElement} nextElement component instance to render
@param {DOMElement} container container to render into
@param {?function} callback function triggered on completion