Make the CompareStub and the UnaryOpStub accept smi inputs.

Make the CompareStub and the UnaryOpStub accept smi inputs.

The stubs get an additional flag for including the smi code
inside the stub. This allows us to generate more compact code
if we don't want to inline the smi case outside the stub.

Review URL: http://codereview.chromium.org/3388005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5456 ce2b1a6d-e550-0410-aec6-3dcde31c8c00