Transition group with multiple classes not working

[ruslansteiger]

Version

3.0.0-alpha.1

Reproduction link

https://github.com/SuddenlyRust/transition-group-with-multiple-classes

Steps to reproduce

npm run serve

Remove or add an item to the list.

What is expected?

Item is added or removed from the list with transition effects.

What is actually happening?

Following exception appears
DOMException: Failed to execute 'add' on 'DOMTokenList': The token provided ('duration-500 ease-out') contains HTML space characters, which are not valid in tokens.

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It looks like multiple classes are not supported in the alpha version but in Vue 2 it is working.

See https://github.com/SuddenlyRust/transition-group-with-multiple-classes/blob/master/src/App.vue#L4

[LinusBorg]

I think we should continue to support that. Will do a quick PR.