UserAgent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:51.0) Gecko/20100101 Firefox/51.0

Example URL:
http://www.gtalbot.org/BrowserBugsSection/CSS3WritingModes/draft-border-collapse-0xy-htb.xht

Steps to reproduce the problem:
2 self-explanatory reduced tests:

http://www.gtalbot.org/BrowserBugsSection/CSS3WritingModes/draft-border-collapse-0xy-htb.xht

http://www.gtalbot.org/BrowserBugsSection/CSS3WritingModes/draft-border-collapse-0xy-vrl.xht

What is the expected behavior?
3 identical multi-colored squares in each test;
beveled borders at corners for all 3 squares of both tests.

What went wrong?
Not identical multi-colored squares in both tests;
no beveled borders at corners for 2 squares in both tests.

Does it occur on multiple sites: N/A

Is it a problem with a plugin? No 

Did this work before? No 

Does this work in other browsers? Yes

Chrome version: 58.0.3013.3  Channel: dev
OS Version: 
Flash Version: irrelevant

Notes
-----

Both tests pass in Chrome 58 if 'border-collapse' is set to 'separate', if you toggle off 'border-collapse: collapse'.

IE10, IE11, Edge13 and Firefox 44+ all pass both tests.

Suggested Component: Blink>Layout>Table