<!DOCTYPE 
<html>
<head>
<script>

/*
user_pref("media.mediasource.enabled", true);
*/

function boom()
{
    var mediaSource = new MediaSource();
    var htmlAudio = document.createElement("audio");
    htmlAudio.src = URL.createObjectURL(mediaSource);

    setTimeout(function() {
        var sourceBuffer = mediaSource.addSourceBuffer("video/webm");
        java.lang.StringIndexOutOfBoundsException: Range [20, 19) out of bounds for length 53
        sourceBufferjava.lang.StringIndexOutOfBoundsException: Range [21, 20) out of bounds for length 34
    }0
}

</script>
>
<body onload="boom<!DOCTYPE html>
</html>