UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.181 Safari/537.36

Steps to reproduce the problem:
1. Load absolute-scroll.html
2. Immediately use the mouse wheel to scroll down a little, until the yellow box is partly off screen (and you can see its bottom somewhere in the middle of the viewport).

What is the expected behavior?
The scripts automatically adds a new line at the top of the yellow box every 200ms.

The container .main must not scroll while the yellow box .positioned expands (until the yellow box is larger than its parent, but with the testcase this takes a while). The yellow box should expand down out of the viewport. The "scroll" event must not be fired by the container .main.

What went wrong?
The yellow box .positioned is absolutely positioned with respect to the container .main, therefore adding content to the child should not scroll the parent, as the child is less tall than the parent.

See absolute-scroll-bad.mp4 for a screencast of the incorrect behavior.

Note that if you skip Step 2 above, the behavior is correct: the container does not scroll while the yellow expands -- until the yellow box reaches the height of the container. See absolute-scroll-good.mp4 for a recording of this case.

Did this work before? N/A 

Does this work in other browsers? Yes

Chrome version: 65.0.3325.181  Channel: stable
OS Version: Arch Linux
Flash Version: 

Firefox 59.0.2 handles this properly: whether the user scrolls the container once manually or not (Step 2), the container does not scroll on its own while the yellow box expands -- until yellow reaches the height of the container, and then the container scrolls down to keep up with the yellow box.
 

Deleted: absolute-scroll.html 8.4 KB

absolute-scroll.html 8.4 KB View Download

Deleted: absolute-scroll-bad.mp4 1.3 MB

	absolute-scroll-bad.mp4 1.3 MB View Download

Deleted: absolute-scroll-good.mp4 321 KB

	absolute-scroll-good.mp4 321 KB View Download