[css-lists] 'marker-side' values have confusing names

[Loirooriol]

https://drafts.csswg.org/css-lists/#marker-side defines marker-side: match-self and marker-side: match-parent.

However, marker-side in an inherited property, so one could set it in the list element like

ol {
  marker-side: match-self;
}

expecting that match-self will use the directionality of the ol. But marker-side applies to the list item, so the author should actually use

ol {
  marker-side: match-parent;
}

even if it may seem to mean that it will use the directionality of ol's parent.

It can also be confusing because direction applies to ::marker. So somebody could think that marker-side: match-self refers to the ::marker and marker-side: match-parent refers to the ::marker's parent (i.e. the list item).

I think something like marker-side: match-list-item and marker-side: match-list would be much clearer.

[fantasai]

See also #4209 which maybe makes the issue less confusing?

Note that the current names were chosen to align with text-align which has a match-parent value, but it's not quite the same situation...