setPolylines method
Replaces the layer's polylines (ids '<layerId>/<index>', painted in list order) right away. Pass them to
MarkerPublisher.publish instead when they belong with a generation of markers (spiderfy legs), so that they
reach the map together.
Implementation
void setPolylines(List<Polyline> polylines) =>
host.registry.setPolylines(layerId, layerPolylines(host.registry, layerId, polylines));