Chrome Version: (Version 64.0.3282.186 (Official Build) (64-bit))
OS: (Win 10)

What steps will reproduce the problem?
(1) go to https://ibma.github.io/Va11yS/WCAG_HTML/H85_example1.html
(2) inspect what is exposed in the accessibility tree for the select elements children
(3)note that the HTML <optgroup>s and their labels are not in the acc tree

What is the expected result?
the <optgroup> elements are exposed as grouping objects and the have an accessible name = to value of their labels attribute.
have a look at the same in Firefox and you will see that this is what is in the acc tree

What happens instead?
the <optgroup> elements are not exposed in the acc tree


related screen reader issue: https://github.com/FreedomScientific/VFO-standards-support/issues/46