Made a few more places use intptr_t instead of int for pointer arithmetic.
Ensure that objects have a declared size that matches heap object alignment.

Review URL: http://codereview.chromium.org/115559


git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2007 ce2b1a6d-e550-0410-aec6-3dcde31c8c00