[css-fonts] Should font-variant-emoji affect ZWJ emoji sequences?

[tursunova]

There are some ZWJ emoji sequences that do not have VS, compare https://www.unicode.org/Public/emoji/latest/emoji-zwj-sequences.txt. Should font-variant-emoji property affect any of the codepoints in these sequences?

Let's consider the following use case:

<div style="font-variant-emoji: text">&#x1F408;&#x200D;&#x2B1B;</div>

According to the CSS Fonts Module 4 spec:

Only the code points listed by Unicode as contributing to a Unicode emoji presentation sequence are affected by this property.

U+1F408 is listed there, since U+1F408 U+FE0E is a valid variation sequence, compare: https://www.unicode.org/Public/15.1.0/ucd/emoji/emoji-variation-sequences.txt.

So the way I interpret spec right now, it example above should act as:

<div">&#x1F408;&#xFE0E;&#x200D;&#x2B1B;</div>

and split the zwj sequence.

Is my understanding correct or do we want font-variant-emoji to not affect any of the codepoints in zwj sequences?

@drott @svgeesus