Separate out code target pointers from normal heap pointer entries in constant
pool arrays so that the GC can correctly relocate these pointers using the
appropriate mechanism.

R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/183883011

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19773 ce2b1a6d-e550-0410-aec6-3dcde31c8c00