There should be a way when comparing two heap snapshots to get a (any / all) path from a retained object to DOMWindow (or some other means to get a hint where e.g. a detached DOM tree is being retained from) There used to be the option to display paths to window instead of to GC roots which is what existing howtos recommend to use: http://gent.ilcore.com/2011/08/finding-memory-leaks.html
Closing as invalid, as this bug pertains to the old inspector UI and/or its tests. Please file a new bug (https://www.webkit.org/new-inspector-bug) if the bug/feature/issue is still relevant to WebKit trunk.