Still stays within the size of Smi and works with a uint32_t bitfield.
Bitfield might need to be extended to handle a larger base.

Review URL: http://codereview.chromium.org/109020


git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1874 ce2b1a6d-e550-0410-aec6-3dcde31c8c00