Bar width ratio and tick values/count

The bar width ratio does not calculate correctly when the number of ticks is different from the number of columns in a bar chart because of using the x tick values or x tick count options.

Here is an example: http://jsfiddle.net/L7od79g3/1/

The bar width ratio seems to be based on the distance between the ticks. I feel that it would be better if the bar width ratio was relative to the width between the columns instead.

Start by reproducing the bar chart from the linked JSFiddle with different x tick values and x tick count options. Trace how the chart calculates bar width relative to tick spacing and column spacing; done means bar widths remain correct when the number of ticks differs from the number of columns.

Written by the indexing model from the issue text.