Paul,
Framesets have been deprecated and are not supported in HTML5 any more. When I tried this code, IE9 automatically switched to Quirks mode (to support the same probably) and threw error. In Quirks mode Canvas is not supported probably.
In my case adding to the top of page containing frameset fixed the issue. But it is not suggested to use framesets anymore.
If required, you should instead use iframe
–
Sunil
