Fixing test failing on IE7/IE8

This commit fixes a test failing on IE7/IE8
DRY principle, I would hav eput the ternary inside the propert access constrcut, like this: 

```javascript
var geometryChild = dom.getGeometry(draggable[(aria.core.Browser.isIE7 || aria.core.Browser.isIE8) ? 'firstChild' : 'firstElementChild']);
```