Conflict with ie8.js

This seems to conflict with IE8.js, in IE7 (at least). You can see it working until IE8.js kicks in then it seems to break.

I know IE8.js is supposed to support box-sizing anyway but that doesn't seem to work with percentages.

Is there anyway we could fix this? Perhaps adding this to IE8.js instead of the current box-sizing fix on there?

Cheers, awesome fix btw! :)
~evu.
