UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:54.0) Gecko/20100101 Firefox/54.0

Steps to reproduce the problem:
click on links in left column to run tests at:
https://www.w3.org/International/tests/repo/results/writing-mode-vertical#rl_forms
https://www.w3.org/International/tests/repo/results/writing-mode-vertical#lr_forms
those tests use both standard and proprietary labels

What is the expected behavior?
see 
https://www.w3.org/International/articles/vertical-text/index#forms_etc
(which also has some test pages (see 'Test in your browser'))

What went wrong?
Vertical orientation is not applied to the forms.

Did this work before? No 

Chrome version: Version 59.0.3071.115 (Official Build) (64-bit)  Channel: n/a
OS Version: OS X 10.11
Flash Version: Shockwave Flash 26.0 r0

It would certainly be good to get this working, since vertical text handling is one of the top priorities in Japan, and it goes without saying that writers of Mongolian websites are severely hampered by lack of support, since their writing system is not designed for horizontal text.