UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.139 Safari/537.36

Steps to reproduce the problem:
1. Randomly when you open a website with lots of markup/content (like the VOGUE website I opened in the video) some black squares appears on the page when scrolling up/down. They blink very fast but if you are lucky enough at stopping the scrolling at a precise time, the black squares keep shown on the page.
2. Check the bug in the video -> https://photos.app.goo.gl/TcXF6YjyZnwrSONp1

What is the expected behavior?
No black squares should be seen.

What went wrong?
Black squares appearing when you open a website with lots of content.

Did this work before? N/A 

Does this work in other browsers? N/A

Chrome version: 66.0.3359.139  Channel: n/a
OS Version: 10.0
Flash Version: