Browser view does not scroll if you drag to the bottom of a drop area that extends below the visible area.

[DBosley]

This only seems to happen in firefox (chrome seems to think you're selecting text when the cursor reaches the bottom, so it does scroll).

Repro steps:

you can see this happen on your examples page
-Navigate to http://one-com.github.io/knockout-dragdrop/examples/ in firefox
-scroll the page so a drag/drop area is half visible/half below the view area
-drag an item to the bottom of the view

Expected: page scrolls with dragging element still held

Actual: page does not scroll