[turbofan] initial framework for unittesting of register allocator

BUG=
R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/683133005

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25071 ce2b1a6d-e550-0410-aec6-3dcde31c8c00