Create AllocationSite objects, pointed to by AllocationSiteInfo.
This creates a platform where we can do additional things with allocation sites,
other than just aid in reducing array transitions.

BUG=
R=hpayer@chromium.org

Review URL: https://codereview.chromium.org/15094018

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15545 ce2b1a6d-e550-0410-aec6-3dcde31c8c00