Fix BitVector test failure.
Fix BitVector test failure.

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: b158db1e4b4ab85d4c9e510fdef4b1e8c614b15b@4072 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh