In case a channel is canceled, it does not fire onerror for iframes. This will become a problem once we rewrite content security policy or also when applying the patch from bug 418354. Right now, onerror is still fired correctly in case shouldLoad blocks a load. Once we account for redirects this will become an issue.

https://bugzilla.mozilla.org/show_bug.cgi?id=1472046 Move all DOM bugs that haven’t been updated in more than 3 years and has no one currently assigned to P5. If you have questions, please contact :mdaly.