Fix for regression introduced by #57 (fling scroll sends click, fix #42)

Starting from 0.5.1 (first version to include #57 fix), the bug fixed by #42 reappeared: tapping on a currently scrolling container with ``-webkit-overflow-scrolling: touch`` sends a click on the underlying element (iOS 6); the expected behavior on iOS would be to just stop scrolling and not fire a click.

I haven't had much time to read through and understand the code (so the change may have side effects) but it restores the behavior of 0.5.0. So please consider this a bug report and adjust as needed.