Fix MSIE8 compatbility problem due to 'default' being a reserved word.

React-Bootstrap was failing in Microsoft IE8 due to this wrapper using the property `.default`.
According to https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Reserved_Words `default` is a reserved word.

This is a workaround for accessing the property anyway.

Please note that I have no idea what I'm doing :)