Animation on transition-group changes in position not working

[neuroactive]

Version

2.5.0

Reproduction link

https://jsfiddle.net/b2cxLdtb/

Steps to reproduce

See the jsfiddle link.

What is expected?

After clicking on an "Up" or "Down" link in the "Actions" column, the row should change position with the adjacent row using an animation taking 2 seconds.

What is actually happening?

The row changes position, but it is immediate.

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This was working in 2.4.4.

[jkzing]

This is some how related to the upgraded rollup build system. I did revert the build system changes and run dev build, it worked. (see: https://github.com/jkzing/vue/tree/revert-upgrade)

Not sure which dev dependency causes this, still needs further investigation.

Here is the new build file: https://raw.githubusercontent.com/jkzing/vue/revert-upgrade/dist/vue.js

[jkzing]

Well, it its caused by rollup@0.50.0. Let's see https://github.com/vuejs/vue/compare/dev...jkzing:revert-upgrade?expand=1#diff-2025d2ea48e750bcd6bafe7ce824a851L8066, line 8069 and 8070 are removed by rollup during tree shaking, which is used to reflow document.