UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.181 Safari/537.36

Steps to reproduce the problem:
1. create a scrollable <div>
2. inside of it put text and a non opaque youtube <iframe> 
3. see the result

What is the expected behavior?
the <iframe> shouldn't bleed out of the parent div

What went wrong?
see this jsfiddle 
https://jsfiddle.net/5zqtrLwe/16/ 
(this doesn't happen on Edge or Firefox)

if you change child opacity to 1, there's no bug

Did this work before? N/A 

Does this work in other browsers? Yes

Chrome version: 65.0.3325.181  Channel: stable
OS Version: 10.0
Flash Version: 

Please don't ask for more info. I work from 4am to around 10pm / 7 days a week. The JSfiddle should be enough