removeChildren method
      
void
removeChildren()
      
     
    
    
Implementation
void removeChildren() {
  if (firstChild == null) {
    return;
  }
  Node? child = firstChild;
  while (child != null) {
    removeBetween(null, child.nextSibling, child);
    notifyNodeRemoved(child);
  }
  ContainerNode thisNode = this;
  thisNode.ensureNodeData().ensureChildNodeList(thisNode).invalidateCache();
}