Duplicate attribute: class in edge and IE

[tdekoning]

Vue.js version

2.0.2

Reproduction Link

http://codepen.io/anon/pen/WGyrdz

Steps to reproduce

Just load up the page in edge or internet explorer (11) with your console open. Vue will display the warning "duplicate attribute: class".
When removing the class attribute, the warning goes away.

What is Expected?

No warnings :). I expect vue to use both the regular class attribute and the :class attribute and merge them together into the class attribute.

[yyx990803]

Actually it's IE that messed up outerHTML by duplicating the attribute :(
I've just disabled this warning for IE.

[tdekoning]

Thanks!

[jdalton]

I'm not able to repro this.

In the simplified test case class and :class show up in the attributes list of
IE11, Edge 14, & Chrome 54.

[Kcharle]

As @jdalton said, this is still an issue in Edge 14.

[posva]

@Kcharle Could you open a new issue with a repro, please? I'm not sure to understand. Does this mean we can remove the check?

[Yangfan2016]

I‘m meeting this too