Also, handlify functions for loading with interceptors and callbacks.
Remove some unneeded code.  Rename Foreign::address() because it
confusingly shadows HeapObject::address() which does something quite
different.

R=vegorov@chromium.org,ulan@chromium.org
BUG=
TEST=

Review URL: http://codereview.chromium.org/8391045

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9834 ce2b1a6d-e550-0410-aec6-3dcde31c8c00