RoundRectDataList ignores the label property in JSON data

[ykami]

Even if a label property that points to the label attribute is specified, labels are not shown in the RoundRectDataList widget. Below is an example data.

var static_data = {
  label: 'name',
  items: [ 
    {name: "Apple",   moveTo: "dummy"},
    {name: "Banana",   moveTo: "dummy"},
    {name: "Cherry",   moveTo: "dummy"},
    {name: "Grape",   moveTo: "dummy"},
    {name: "Kiwi",   moveTo: "dummy"},
    {name: "Lemon",   moveTo: "dummy"},
    {name: "Melon",   moveTo: "dummy"},
    {name: "Orange",   moveTo: "dummy"},
    {name: "Peach",   moveTo: "dummy"}
  ]
};

[ykami]

(In [24200]) Fixes #12604 !strict. Use getLabel() if the label property is available.