The problem occurs in chromium trunk build (chromium r132979, WebKit r114621).
1. Open some web page using JS.
2. Bring up developer tools -> Profiles -> New heap snapshot.
3. Expand some objects in the object list, click several objects.
The "Object's retainer view" doesn't get cleared when the selected object changes, but the retainers of the selected object are added to it. The retainers of all the clicked objects accumulate in the view.
Created attachment 137937 [details]
Committed r114662: <http://trac.webkit.org/changeset/114662>