QChart: Make it easier to showing axes ranges without any data

Currently, the only way to show axes without any data is by adding a dummy blank series:

auto dummySeries = new QLineSeries;

auto chart = new QChart();
chart->addSeries(dummySeries);
chart->createDefaultAxes();
chart->axes(Qt::Horizontal).first()->setRange(-20, 20);
chart->axes(Qt::Vertical).first()->setRange(-10, 10);

dummySeries->deleteLater();

It would be good if dummySeries is not needed.

Use-case

The customer would like to show a blank fixed-range chart first, and then dynamically add an arbitrary number of series later.