Support for the loadend event is needed. For example, see http://www.w3.org/TR/XMLHttpRequest2/#event-handlers.
This bug report is per https://bugs.webkit.org/show_bug.cgi?id=40952#c23.
It looks like the scope of the new bug could be expanded to include support for loadstart, progress, abort, error events dispatched for both XMLHttpRequest and XMLHttpRequestUpload. And I would think that the support would be similar to the code included for the load event in XMLHttpRequest::callReadyStateChangeListener(). A little factoring would be required to avoid ballooning the implementation.
Does this sound reasonable?
Closing as invalid, as this bug pertains to the old inspector UI and/or its tests.
Please file a new bug (https://www.webkit.org/new-inspector-bug) if the bug/feature/issue is still relevant to WebKit trunk.