ColumnChart: Data with only negative values has misplaced bars

[DavidMoerman]

Describe the bug
I have modified the example-negative-value.html file from the demo, to a dataset with just two negative values:

    var negativedataset = [{
            data: [{
                name: 'Automotive',
                shortName: 'Auto',
                abbrName: 'A',
                value: -7
            }, {
                name: 'Distribution',
                shortName: 'Dist',
                abbrName: 'D',
                value: -5
            }
          ]
          }];
 
    $('#column-bar-example').chart({type: 'column', dataset: negativedataset});

If I alter the dataset slightly by adding a third bar that has a zero value, the chart looks like this:

This last chart is how I would expect the first one to look like as well (but then just with two bars, of course).