The bug appears both in chromium trunk build (chromium r132979, WebKit r114621) and in Google Chrome 20.0.1105.0 dev.
1. Navigate to a page using JS. A static page with no interactions will do.
2. Take 3 heap snapshots.
3. Select snapshot 3, and display "Objects allocated before Snapshot 1".
The view is empty. It should contain the same objects as snapshot 1. (Nothing was disposed.)
Alternatively, use a page, and do something that allocates new objects between the snapshots. Then the "Objects allocated between snapshots 1 and 2" and "Objects allocated between snapshots 2 and 3" views should also be nonempty, but they are empty, too.
Created attachment 137933 [details]
Committed r114658: <http://trac.webkit.org/changeset/114658>