[pointer-animations] Minor syntax suggestions

[cdoublev]

<axis> is already defined in Scroll Animations, which is a problem for CSS tools like w3c/webref and its users (like MDN). Not sure what is the best solution. Perhaps it could be defined in CSS Logical. At worst, it should be defined only once.

<source> expands to the same keywords than <scroller> in Scroll Animations. Besides, "source" seems a bit general, which could prevent using this production name with other values in other contexts. Perhaps both could be replaced with <animation-timeline-root> or whatever production name would be appropriate?

[AtkinsSJ]

I noticed this is already partly addressed in #12283. cc @tidoust

[ydaniv]

Thanks @cdoublev! I approved #12283 which addresses both.
Ideally <axis> could probably be reused for both SDA and PDA.
And <source> should be prefixed, like in the PR above.

[cdoublev]

Alright. The main issue was the duplication of <axis> definitions. So closing as fixed by #12283 then.

Two other suggestions though...

<axis> could be used in the value definition of *-timeline-axis.

animation-range-center is defined with <animation-range-name> below its definition table. I guess it should be <timeline-range-center-subject>, like in the definition table.