UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/59.0.3035.0 Safari/537.36

Example URL:
http://codepen.io/tcschiller/pen/Qpdbjo

Steps to reproduce the problem:
The above codepen shows the issue. If flex on the element itself or table on the ::before element is removed, content renders correctly.

What is the expected behavior?
Content should render inside its content box.

What went wrong?
The content box is positioned correctly on the canvas, but its content renders outside it when the css display values above are both applied.

Does it occur on multiple sites: Yes

Is it a problem with a plugin? No 

Did this work before? Yes Unknown. This seems like a recent issue. It's in canary only so far.

Does this work in other browsers? Yes

Chrome version: 59.0.3035.0  Channel: canary
OS Version: OS X 10.12.3
Flash Version: