fixed 'null' is not an object in .../ui/appframework.ui.js, line 3015

in af.touchlayer.js

Hi Ian,

I've got this exception on an iPhone 5 with iOS 6.1.4 while testing my dialogs. It appears (sometimes/often) if a select box got focus, the wheel-picker appeared and the screen was scrolled.

This patch seems to prevent this, but I'm not sure if it isn't better to just return if this.scrollTimeoutEl_ is null. What do you think Ian?