iPad modal <select> bug

Created by: ghost

When popping up a modal on a page that is scrolled down, then opening a <select> within the modal, the page jumps up. All elements on the modal are shifted in a way that they no longer line up with the actual visuals. It's tough to explain, so I put together a demo:

https://github.com/CaptSaltyJack/bootstrap-select-bug

Once it's broken and the modal button and dropdown no longer work, try tapping slightly above them. You'll see what I mean about the touch areas being displaced. Once you scroll to the top of the page, the modal elements work again as expected.