SliverOverlapAbsorber constructor
Creates a sliver that absorbs overlap and reports it to a SliverOverlapAbsorberHandle.
The handle
must not be null.
The child
must be a sliver.
Implementation
const SliverOverlapAbsorber({
Key key,
@required this.handle,
Widget child,
}) : assert(handle != null),
super(key: key, child: child);