Interval on line 207 doesn't get cleared

When dragging the layout quite fast the layout there's an interval that doesn't get cleared and it's executing all the time.

You can see it on line 207

```
cache.animatingInterval = setInterval(function() {
utils.dispatchEvent('animating');
}, 1);
```

This can be achieved in either android devices or iOS devices, but it's especially easy to do it on iOS since the webview can bounce.

Here's a link to a json ( https://gist.github.com/pablocaselas/5755857 ) you can use to import on chrome dev tools to see what I mean. When I recorded this event, I was actually not touching the device (a nexus 7).

Did anybody run into this issue yet?

Start at the interval shown on line 207 and reproduce the fast-drag behavior using the linked Chrome DevTools recording, especially on iOS or Android webviews. Trace where cache.animatingInterval is created and cleared, then verify that a completed drag does not leave the interval executing continuously.

Written by the indexing model from the issue text.