[css-writing-modes] The interaction between display:contents and unicode-bidi should be clearly defined and tested #9897
Description
The interaction between the unicode-bidi property and display: contents should probably be defined more clearly than it is today, and also tested. In at least Chrome, at least some values of unicode-bidi work on elements that are display: contents. We should both decide what the desired behavior is and make sure there are tests for it. (There may be some behaviors that are clearly defined today because of explicit wording in the spec that was written before display: contents existed, but those definitions may not really be what we want.)
(This came from a review comment I made on a Chromium CL.)