Fix for a Mac build issue after r20846.

R=yangguo@chromium.org

Review URL: https://codereview.chromium.org/241013002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@20848 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Make Heap::AllocateRaw private.

R=yangguo@chromium.org

Review URL: https://codereview.chromium.org/238443016

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@20849 ce2b1a6d-e550-0410-aec6-3dcde31c8c00