Scrolling to top if content changed and is not exceeding panel height.

Use case before fix/workaround:
1. A list that doesn't exceed the panel height, hence the scroller is disabled.
2. Hidden div gets shown by showHide() -> content exceeds panel height -> scroller enabled.
3. User scrolls down, top of the page not visible anymore. 
4. Hiding a div -> content NOT exceeding panel height -> scroller disabled, but top of the page still not visible.
5. Because the scroller is disabled it's not possible to get back to top of the page.

After fix/workaround:
1-4 see above
5. On the next touch the page scrolls to top.

I know this solution is not perfect, because it needs a second touch event after the some content get's hidden, but this doesn't render the panel useless at least.

Sorry for not minifying, I don't know how that's done. I hope you don't mind and can do that yourself.

This is my first pull request ever and the first commit to a repo other than my own. I hope I did everything the way it's supposed to be.

PS: Thanks for the best framework of all!