The stats data have only count field at the moment.
A constantly growing array of integers also can be a reason of a leak.
Ans we have to have a way to detect such kind of leaks.

Drive by fix:
FindObject and AddEntry were replaced with FindEntry/FindOrAddEntry pair.

BUG=none
TEST=HeapSnapshotObjectsStats

Review URL: https://chromiumcodereview.appspot.com/10086004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11327 ce2b1a6d-e550-0410-aec6-3dcde31c8c00