When a CompositeAnimation creates a new transition for a property, it removes an existing transition if one exists. At the moment it simply deletes it from its list, but since it could potentially be in the list of animations waiting for start time, it isn't being cleared. <rdar://problem/9326422>
Created attachment 92139 [details] Sample test Incomplete test
Created attachment 92156 [details] Patch
http://trac.webkit.org/changeset/85693