Pass a Code object to Assembler::(set_)target_address_at for use by ool constant pool.

The ool constant pool will require a pointer to the code's constant pool when
updating or reading target addresses using set_target_address_at()
and target_address_at().

R=ulan@chromium.org

Review URL: https://codereview.chromium.org/183803022

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19825 ce2b1a6d-e550-0410-aec6-3dcde31c8c00