MIPS: Separate Cell and PropertyCell spaces

Port r15089 (5c28e4e7)

Original commit message:
This makes it possible to store additional information on property cells, for example Type and optimized Code dependencies.

BUG=

Review URL: https://codereview.chromium.org/16858003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15103 ce2b1a6d-e550-0410-aec6-3dcde31c8c00