Deopted on zero result, not just bad cvttsi2sd conversion.
Add inline floating point result for SHR in Smi TypeRecordingBinaryOpStub.
Small optimizations.

Adding rightshift to case handled by floating point result in type-recording binary op stub.

Review URL: http://codereview.chromium.org/6801040

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@7537 ce2b1a6d-e550-0410-aec6-3dcde31c8c00