[css-overflow-5] Missing determine scroll-into-view params? #12136

The example on how to determine the active scroll marker in the css-overflow-5 spec directs user agents to run the determine-the-scroll-into-view-position algorithm but does not provide block and inline arguments which determine the alignment of the scroll container with its subject and default to "nearest".

I believe the intention for snap targets was to use the alignment indicated by scroll-snap-align but for non-snap targets, it seems we'd naturally be defaulting to "nearest". However, "nearest" might not be the best option as it means the target position, which is used to determine whether a target is within half a scroll port from the current scroll position, might have the target outside the viewport. I.e. the "nearest" scroll position that brings the element into view might be half a scroll port away from the current scroll position while the target's position itself is not. (See demo)

I propose we we have the algorithm supply "start" block and inline values as these would ensure that the target is within view when selected.