[Resource Timing] Indicating Failed Requests

I've been experimenting with IE8's implementation of Resource Timing...

In one test I created a page where the browser would never receive a
response for one resource and so would eventually time the request out
(used blackhole.webpagetest.org with a blocking third party script)

In another, I just created a test page with a missing resource.

In both cases the request and timing information is included in the RT
entries but there's no indication of whether the request was a success or
failure and I wonder if there should be one.

For example, if a request for an resource is really fast, was it because
the    resource was retrieved quickly or that the resource doesn't exist
and an error response delivered?

Cheers

Andy