Message from "oneplusone": Preview does not load in Firefox when it is hidden

[sunghwan2789]

The preview doesn't load in Firefox when it is hidden, like in a spoilerbox. I get this error

It works fine on chrome.

---

$("#songinfo").parent().next().after(
    $("<div class='spoiler'></div>").append(
        $("<div class='spoiler_head' onclick='return toggleSpoiler(this);'>osu!preview</div>"),
        $("<div class='spoiler_body'></div>").append(
            $("<iframe class='osupreview' src='https://bloodcat.com/osu/preview.html#164020' allowfullscreen></iframe>")
        )
    )
);

It fails on Firefox 44.0

[sunghwan2789]

Firefox's bug: https://bugzilla.mozilla.org/show_bug.cgi?id=941146