Duplicate attribute class in MS Edge #5394
Description
Version
2.2.6
Reproduction link
http://codepen.io/anon/pen/WGyrdz
Steps to reproduce
Open the codepen with MS Edge devtools open
What is expected?
No warning. When you execute el.outerHTML within vuejs while the element is being mounted, you will see that the class attribute is duplicated.
What is actually happening?
A warning (duplicate attribute class)
This has been dealt with in #3929 already but it seems that MS Edge 38 is not correctly handled.