Fix stacked combo bar charts & add test

[etimberg]

Fixes #1862

[cdwilhelm]

@etimberg thank you. when does Chart.js get updated in v2.0-dev branch?

[etimberg]

@cdwilhelm I just pushed up copies of the built files

[cdwilhelm]

@etimberg thank you, that indeed solve the problem I reported. Thank you for the quick turn around.
I updated my chart to have multiple lines as y-axes and removed the stack. with that change the x-axes loses data. Is this another bug or do I need to change some params? I didn't see anything that may have helped me.

[etimberg]

@cdwilhelm can you create a JSfiddle or post your config?

[cdwilhelm]

@etimberg oh sorry. https://fiddle.jshell.net/cwilhelm/whva3opt/

[etimberg]

@cdwilhelm the X axis is still marked as stacked. Setting it to false is what you'd want.

[cdwilhelm]

@etimberg yes, that is true. I'm looking to have x-axes stacked, but not the y-axes. my use case will have many bar datasets and it will be better represented as a stacked bar then individual bars.

When the x-axes has stacked: true, the bars are not represented as described in the datasets. for example Jan should should show 1 from each dataset (red and green bar) the others are not shown correctly either, each are missing data or not correctly calculated.

[etimberg]

@cdwilhelm Ah, ok. I see what you're looking for. When only the x axis is stacked, the bars draw on top of each other which is why you only see one. When the y axis is stacked, the bars display correctly but then the lines also stack. I can think of a couple of work-arounds, but none seem ideal. Can you please file a separate issue for this?

[cdwilhelm]

@etimberg I sure will, thanks for the evaluation and all the help.