ENYO-483: Handle onStabilize event in MoonScrollStrategy.

### Issue
With the recent optimizations for scrolling, there was an issue with the scroll position not updating properly after scrollable content size had changed.

### Fix
We ensure that `scrollMath` in `MoonScrollStrategy` handles the `onStabilize` event.

Enyo-DCO-1.1-Signed-off-by: Aaron Tam <aaron.tam@lge.com>