A/B-testing: Archived Tests gadget does not work in IE

Description

Steps to reproduce

1. Create a new Alloy site with the latest Episerver version, as of 2017-09-04.
2. Install the latest A/B testing nuget package, as of 2017-09-04.
3. Go to edit mode in IE 11.
4. Add the gadget "Archived Tests".

Expected: Edit mode works normally.

Actual: Edit mode does not work for that user in IE. You see a js error in the console.