Avoid selecting SVG elements without class names in updateDataMarks.

[samussiah]

for instance in drawBars:

• line 35
• line 132
• line 231
• line 304

if any custom rect elements are added to these bar groups the new and original elements behave unpredictably

[jwildfire]

Hmm. Makes sense, but also seems like a bit of an edge case, since I'm not sure if we've ever manually added rects to a bargroup. Marking low priority unless you disagree, @samussiah.

I guess easy solution would be to give the webcharts rect objects used in the code above a specific class, and then use it in those selectors. Or better yet, use marks[].rect.