Bar plot: singular datapoint bar not visible when xaxis is set to a fixed range

[GlennMatthys]

Example: https://jsfiddle.net/mo65wevq/

When plotting a bar graph with only one datapoint and the xaxis set to a fixed range, no bar is seen on the chart. When a second data element is added, the bar becomes visible. Expected behavior: a bar chart with a single datapoint shows one bar.

Note that the second datapoint doesn't have to contain data, its Y value can be null. There just has to be a second datapoint for the bar graph to work.

[etpinard]

Looks like a duplicate of #1346

[etpinard]

merged into #1346