Although ... [this page](https://developer.mozilla.org/en-US/docs/DOM/XMLHttpRequest/Using_XMLHttpRequest) seems to show an `alert()` being used with a `loadend` event that would be fired after `abort` I assume. 

It seems like the current code is being wisely conservative and using a subset of XHR that is proven to work across browsers. It would be worthwhile to get the XHR spec to clarify these cases so we can use them in a decade or so.