1) symbolic names for the register (like, edx == receiver)
2) can return an array of registers
3) defines ordering when passed on the stack

Code that implements or uses the IC should use this RegisterSpec instead of "knowing" what the registers are. Or at least have the RegisterSpec to validate it's assumptions.

R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/340363002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21939 ce2b1a6d-e550-0410-aec6-3dcde31c8c00