addIceCandidate behavior

We've had some implementors express confusion about the behavior that 
addIceCandidate should exhibit. The current spec says this:

> If the candidate parameter is malformed, throw a |SyntaxError| 
> exception and abort these steps.
>
> If the candidate is successfully applied, the user agent /MUST/ queue 
> a task to invoke successCallback.
>
> If the candidate could not be successfully applied, the user agent 
> /MUST/ queue a task to invoke failureCallback with a |DOMError| object 
> whose |name| attribute has the value TBD.
>

Given that we're passing in an RTCIceCandidate as the parameter, it's 
not clear to me what "malformed" might mean. Is an RTCIceCandidate with 
a null "candidate" attribute "malformed"? Or is that simply a candidate 
that "could not be successfully applied"? Or, for that matter, do we 
consider processing of an RTCIceCandidate with a null candidate 
attribute to be successful?

/a