<audio> tag not in DOM fails in IE8

In IE8 if you create an `<audio>` element outside of the document it will behave different then in modern browsers.
Let's say we create and initialise the element like this:
```javascript
var element = $('<audio src="jo.mp3" />')[0];
new MediaElement(element);
```

In IE8 the element's `parentNode` will be set to a `HTMLDocument` object, which has no `tagName` property, so the following code will fail:
```javascript
node = htmlMediaElement.parentNode;
while (node !== null && node.tagName.toLowerCase() != 'body') {
```