Using the same technique as Leaflet, this relays MSPointer events to touch
events. Using the simulator, I can verify that even pinch-zoom works with
this change, but the visual experience is a bit jumpy. Would be great if
people could test this on physical touch devices and see how it looks/feels
there.
In current Webkit browsers, having translate3d on svg child elements
causes the positioning from the layer not to be inherited by the vector
layer content.