stop pan key event even when pan anim is in progress (#6231)
stop pan key event even when pan anim is in progress (#6231)

When pressing pan key multiple times while pan animation is in progress, `stop` function isn't invoked.
This led to document scroll (if document is scrollable)

This commit fixes the issue to stop pan key event even when pan animation is in progress.
stefanocudini/Leaflet,Leaflet/Leaflet,CapeSepias/Leaflet,CapeSepias/Leaflet,Leaflet/Leaflet,CapeSepias/Leaflet,stefanocudini/Leaflet,stefanocudini/Leaflet,Leaflet/Leaflet