r4071 made BitVector zone-allocated, but the BitVector tests were not
changed to allocate a Zone.

Review URL: http://codereview.chromium.org/818001

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4072 ce2b1a6d-e550-0410-aec6-3dcde31c8c00