I've noticed a few times recently messages from the Objective-C runtime about autoreleased objects being leaked due to there being no autorelease pool in place. In a debugger I determined that the objects in question are allocated on the WebCore scrolling thread from within AppKit. The ScrollingThread class does not appear to set up any autorelease pool for code that is called by its runloop source.
Created attachment 159880 [details]
Comment on attachment 159880 [details]
Clearing flags on attachment: 159880
Committed r126326: <http://trac.webkit.org/changeset/126326>
All reviewed patches have been landed. Closing bug.