EME-protected VIDEO element and drawImage

There is a slight issue wit EME protected and Canvas, since EME-protected
content may not be drawable, because it is protected.

There are already provisions in the Canvas2DContext specification which are
already nearly able to deal with this issue, but they're a little to
narrowly defined.

Specifically:

http://www.w3.org/TR/2dcontext/#dom-context-2d-drawimage :
"If the image argument is an HTMLImageElement object that is not fully
decodable, or if the image argument is an HTMLVideoElement object whose
readyState attribute is either HAVE_NOTHING or HAVE_METADATA, then the
implementation must return without drawing anything."

EME does not affect the readyState, but it may not be fully decodable.
Problem is, that condition only applies to HTMLImageElement. I would
suggest we change it, so that it applies to HTMLVideoElement as well:

"If the image argument is an HTMLImageElement or HTMLVideoElement object
that is not fully decodable, or if the image argument is an
HTMLVideoElementobject whose
readyState attribute is either HAVE_NOTHING or HAVE_METADATA, then the
implementation must return without drawing anything."

Does anybody see any issues with that?

--hans