Comment 18 for bug 243520

(In reply to comment #15)
> (From update of attachment 326964 [details])
> Are you sure aFrame is never null when nsObjectLoadingContent::HasNewFrame is
> called?

Yes, the only caller:

http://mxr.mozilla.org/mozilla-central/source/layout/generic/nsObjectFrame.cpp#1060

always passes in |this|, and passing no frame to HasNewFrame() makes no sense to me.