"Non-zero bound Axis" doesn't work if values are around 0

[palkatap]

I modified the example code in nonzero_bound_measure_axis.dart as follows:

static List<charts.Series<MyRow, DateTime>> _createRandomData() {
final random = new Random();
final int base = 100;

final data = [
  new MyRow(new DateTime(2017, 9, 25), random.nextInt(100) + base),
  new MyRow(new DateTime(2017, 9, 26), random.nextInt(100) + base),
  new MyRow(new DateTime(2017, 9, 27), random.nextInt(100) + base),
  new MyRow(new DateTime(2017, 9, 28), random.nextInt(100) + base),
  new MyRow(new DateTime(2017, 9, 29), random.nextInt(100) + base),
  new MyRow(new DateTime(2017, 9, 30), random.nextInt(100) + base),
  new MyRow(new DateTime(2017, 10, 01), random.nextInt(100) + base),
  new MyRow(new DateTime(2017, 10, 02), random.nextInt(100) + base),
  new MyRow(new DateTime(2017, 10, 03), random.nextInt(100) + base),
  new MyRow(new DateTime(2017, 10, 04), random.nextInt(100) + base),
  new MyRow(new DateTime(2017, 10, 05), random.nextInt(100) + base),
];

It works if base > 0 or base < -100 but not if base is around -50