Collapse doesn't animate on first open

[pdesoyres]

Environment

• Package version(s): 3.19.1
• Browser and OS versions: Google Chrome 77.0.3865.120, Linux Mint 19

Steps to reproduce

1. clone git blueprint repository
2. run yarn
3. run yarn verify
4. run yarn dev
5. navigate to http://localhost:9000/#core/components/collapse
6. click on the "Show build logs" button

Actual behavior

The first Collapse opening is not animated. All other successive close and open plays animation properly.

Expected behavior

An animation should be played at first opening

Possible solution

Exact same issue (#2911) has been fixed but the commit 8ce4d59 introduced the regression.

[alxmiron]

Same for me. Animation regression

[renzholy]

Same for me

[mytototo]

I have the same issue and want to add a little detail about it: after upgrading to latest version, the closing animation doesn't work at all regardless if it's the first opening or not (it closes well but without the expected animation).

[adidahiya]

Fixed by #3831. Note that this also fixes Tree animations as well