UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.181 Safari/537.36

Steps to reproduce the problem:
I have created a codepen which I am referencing in the steps below. 
https://codepen.io/GiggleSnortsTheGalaxyPrincess/pen/XEwWwz

1. Ensure that the displayed document is of a small enough size that the pen has a scroll bar. 
2. Place your mouse in the red outlined element above the green outlined element.
3. Scroll down across the green outlined element with a trackpad or scroll wheel without moving the mouse at all. You will notice that the document continues to scroll once the mouse enters the green element, rather then the green element itself. The green element will only scroll once you have moved the mouse or clicked with the mouse over the green element. 

A similar issue with scroll chaining can be observed. 

1. Ensure that both the document and green element are scrolled all the way to the top. 
2. Place your mouse inside the green element and again scroll down without moving the mouse at all. You will notice that once you scroll down fully in the green element the document will not continue to scroll down until you have moved the mouse, even with `overscroll-behavior: auto;`

What is the expected behavior?
You should not have to make a mouse interaction for the element which is scrolling to change. 

When scrolling past an element as soon as the mouse enters the element, that element should begin to scroll instead. 

When scrolling to the top or bottom of an element with the default over-scroll behaviour, the outer element should then begin to scroll. 

These are especially noticeable when scrolling with a track pad as often trackpad scrolling will cause the mouse position to remain fixed. 

What went wrong?
Its seems that anytime in which the element which is being scrolled by the mouse-wheel or trackpad has to change, it is not properly changing until a mouse interaction is made. 

Did this work before? Yes 64.0.3282.140

Does this work in other browsers? Yes

Chrome version: 65.0.3325.181  Channel: stable
OS Version: OS X 10.13.3
Flash Version: Shockwave Flash 29.0 r0

I have tested this issue in Chrome 65.0.3325.181 and Canary 67.0.3395.0 in which this problem occurs. 

I have also tested this issue in 64.0.3282.140 and a few previous versions and the above described expected behaviour occurs.