[cssom-view] offsetX/offsetY should define behavior when the target node has no box

This includes both cases when there was no box at the start of event 
dispatch, if that case is relevant, and cases when the box goes away 
during event dispatch before offset* is read.  Right now implementations 
are not interoperable in the latter situation.

-Boris

Received on Thursday, 15 March 2012 13:34:31 UTC