Remove unnecessary HCompareNumericAndBranch when generating HShr instruction.

R=verwaest@chromium.org

Review URL: https://codereview.chromium.org/334573003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21799 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Rename kIs64BitArch with kRequiresCodeRange.

R=verwaest@chromium.org

Review URL: https://codereview.chromium.org/335473003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21800 ce2b1a6d-e550-0410-aec6-3dcde31c8c00