Rx.DOM.load() not triggered on <iframe> element

[martinsik]

I made this little demo on jsfiddle: https://jsfiddle.net/usualcarrot/4tfLm050/3/
I seems like the load is never called:

<iframe id="my-iframe" src="https://httpbin.org/get?1"></iframe>

var iframe = document.querySelector('#my-iframe');

Rx.DOM.load(iframe).subscribe(function() {
    console.log('iframe ready');
});

I can see in Chrome's Developer Tools that the event listener is created but it's never called. Am I just doing it wrong?