detachRenderObject method Null safety
Remove renderObject from the render tree.
The default implementation of this function simply calls detachRenderObject recursively on each child. The RenderObjectElement.detachRenderObject override does the actual work of removing renderObject from the render tree.
This is called by deactivateChild.
Implementation
void detachRenderObject() {
visitChildren((Element child) {
child.detachRenderObject();
});
_slot = null;
}