CSS Writing Modes Level 3 without "webkit" prefix, along with syntax updates to the most recent CR. As part of the work, a non-standard value "horizontal-bt" is removed from -webkit-writing-mode.
Docs: https://docs.google.com/document/d/1lGrcTSlKMDeOEKZbHqvdLnW_Soywn7oICci2ApBXB00/edit?usp=sharing https://developer.mozilla.org/en-US/docs/Web/CSS/unicode-bidi https://developer.mozilla.org/en-US/docs/Web/CSS/writing-mode https://developer.mozilla.org/en-US/docs/Web/CSS/text-orientation https://developer.mozilla.org/en-US/docs/Web/CSS/text-combine-upright