add method
Adds or updates a child and its positioning data.
Implementation
void add(RenderBox child, {StackChildData data = const StackChildData()}) {
_validateData(data);
if (identical(child.parent, this)) {
if (_childData[child] != data) {
_childData[child] = data;
markNeedsLayout();
}
return;
}
adoptChild(child);
_childData[child] = data;
}