Scroller: fixed a problem when you call the stopScrolling method. After ...

...that, SCROLL event isn't dispatched until it dispatches SCROLL_COMPLETE event with user interaction.

I was using a list with a external SimpleScrollBar (i needed a position and size different that list), then I handled manually the scroll.

Steps to reply the problem:
1. User interacts with list, keeping it with inertia.
2. While the list has inertia, user interacts with the thumb of the scrollbar. It calls stopScrolling method.
3. User finishes touch the thumb. 
4. User interacts with list again, but Event.SCROLL isn't dispatched, then the thumb position can't be positioned. When the inertia of list is finished, if user interacts with it again, it works (Event.SCROLL is dispatched).