Don't be confused into thinking that, in this case, "North America" means the whole of the North of the continent (i.e USA and Canada)
The VWP 90 day stay limit applies to the USA, not Canada, so I don't see you will have any problems at all with the VWP provided you can prove (on arrival) that you will be exiting the USA before the 90 days is up. This could be by way of pre-booked travel ticket (rail/plane etc.) and prior hotel booking at a Canadian destination. They want to be sure you have firm plans to leave, before they let you in!!
Don't forget that now you have to register, at least 72 hours before travel to the USA, via the online ESTA system (as part of the VWP).
https://esta.cbp.dhs.gov/