Creates a render box that automatically sizes and positions its children.
Source
RenderAutoLayout({
AutoLayoutDelegate delegate,
List<RenderBox> children
}) : _delegate = delegate, _needToUpdateConstraints = (delegate != null) {
_solver.addEditVariables(<al.Variable>[
_rect.left.variable,
_rect.right.variable,
_rect.top.variable,
_rect.bottom.variable
], al.Priority.required - 1);
addAll(children);
}