function unmountComponentFromNode(instance, container, safely) {
  if (process.env.NODE_ENV !== 'production') {
    ReactInstrumentation.debugTool.onBeginFlush();
  }
  ReactReconciler.unmountComponent(instance, safely);
  if (process.env.NODE_ENV !== 'production') {
    ReactInstrumentation.debugTool.onEndFlush();
  }

  if (container.nodeType === DOC_NODE_TYPE) {
    container = container.documentElement;
  }

  // http://jsperf.com/emptying-a-node
  while (container.lastChild) {
    container.removeChild(container.lastChild);
  }
}
Used by devtools. The keys are not important.