We tracked this down in response to a bug that eliminated the "Browse Server" button when you tried to create an image but didn't place focus in the editor before hitting the image button. The Selection object representing what's currently selected didn't have any ranges in it, raising an exception under webkit when it tried to call Selection.getRangeAt(0).

The other was a javascript exception that was always popping up on page load on webkit browsers (Chrome/Safari).

Patches are included (applied against today's magnolia trunk).