Today's lesson in not using Apple's private methods: somewhere between old/886f95f00431 and #9620 Apple changed their document icon setup process. Use the new methods and fix #9620.
(transplanted from 5cf365ce9352d25978ffd6073d3bc07573aba518)
/*
* Generated by class-dump 3.3.3 (64 bit).
*
* class-dump is Copyright (C) 1997-1998, 2000-2001, 2004-2010 by Steve Nygard.