Quickly opening and closing sidebar changes it's width

Reproduction steps:

1. Show sidebar and make it quite wide
2. Hide sidebar
3. Show sidebar and hide it before animation reaches the full width (easy with the hotkey)
4. Show sidebar again

Expected result:
Sidebar is as wide as after step 1.

Actual result:
Sidebar is as wide as it was wide when hide was pressed in step 3

Sidebar is as wide as after step 1.

0.99.126.4-beta (WebKit 618.1.2)

Sonoma (14)