It seems that there will be no access to heap snapshots from
web pages' code, only from Developer Tools, thus it makes no
sense doing filtering of object by their security contexts.

Review URL: http://codereview.chromium.org/4681003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5787 ce2b1a6d-e550-0410-aec6-3dcde31c8c00