Problem: Displaying stacked (grouped) timeseries chart with dashed regions

**_Chrome 41, FF 36 and IE11, too**_

I came upon this error when I tried to do the thing the title says. Unfortunately I was unable to "_extract_" the problem sample to a higher (more specific) degree, so I'm giving it nearly all out.

**Fiddle:** http://jsfiddle.net/dwq40swy/

**Screen:**

Start by reproducing the grouped timeseries chart with dashed regions from the linked JSFiddle in Chrome, Firefox, and IE11, comparing the result with the attached screenshot. Identify the rendering failure and verify that the chart displays the stacked series and dashed regions correctly in the affected browsers.

Written by the indexing model from the issue text.