vnode's className is mixed when an empty object is shared as attrs of vnodes.

[kfule]

Mithril.js version:2.2.3

Browser and OS:

Code

https://flems.io/#0=N4IgZglgNgpgziAXAbVAOwIYFsZJAOgAsAXLKEAGhAGMB7NYmBvEAXwvW10QICsEqdBk2J4hcYgAI4hDACcYAEwCiWAA7EAngEFixOXEkBeScFYAdNJfFSMxyVgAUAcnwZnFabIUr1W3fpwAJTW9BKSAEb2Tq4RHl7ySqoaOnoGIVZoAPRZkW5pcPjUUBhwcAByXF60AK5QipEwkuYgES0A-KFocLSw+FC0AOaOEfmBRSVllTgZlCBwMLDUxBBheACsiADM62wcIJg4eEVlc0KMzDxsALpUUBBoANYIKJxHPFgQxIRy0AACACZ8ECtnManJyDwSMQ1HBEDkamg1I9BkVaFgsp9vr8oIDgfgtpivj9oPhPmh8Pw5lo1Nx5tRfhobqwgA

Steps to Reproduce

1. define empty object
2. share 1's empty object for attrs of multiple hyperscripts with selector having class name

Expected Behavior

The vnode class name will be the one defined in the respective selector.

Current Behavior

The class names defined in the selector of each vnode are mixed.

Context

I discovered this in the process of creating the following pr.
#2819

[pygy]

Great catch! I thought we were doing that safely :-/