MovementX/Y values in coalesced events

[mustaqahmed]

The PointerLock extension defining movementX/Y also applies to PointerEvents (as a subclass of MouseEvent), and that calls for a clarification in movementX/Y values "around" coalesced events.

When Chrome decides not to send all pointermove events for performance reasons, the dispatched event's movementX (movementY) is updated to be the sum of individual movementX values (respectively movementY values) in coalesced events.

Should we add a line in the PointerLock spec mentioning it?

In PointerEvents spec, we had a non-normative text mentioning this idea but PEWG today decided that it does not belong there. In my opinion, the PointerLock spec should mention it because it would be useful for developers who care about movementX/Y values in individual coalesced events.