function findDeepestCachedAncestorImpl(ancestorID) {
  var ancestor = nodeCache[ancestorID];
  if (ancestor && isValid(ancestor, ancestorID)) {
    deepestNodeSoFar = ancestor;
  } else {
    // This node isn't populated in the cache, so presumably none of its
    // descendants are. Break out of the loop.
    return false;
  }
}
Register a component into the instance map and starts scroll value
monitoring
@param {ReactComponent} nextComponent component instance to render
@param {DOMElement} container container to render into
@return {string} reactRoot ID prefix