Scroll area doesn't respect last elements bottom margin

In app on iOS and Android the way the height of the scroll element is calculated doesn't include the bottom margin of the last element. It works correctly on OS X in Chrome but you can still see the issue in Safari.

This can be easily recreated by adding enough content to a scroll item to make it scrollable and adding margin bottom to the last element.

http://codepen.io/lukechilds/pen/xucld
