This is to avoid triggering an assertion from Smi::FromInt. The
generated code is unreachable, so it is not a real bug.

R=ulan@chromium.org
BUG=

Review URL: https://codereview.chromium.org/221743005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@20458 ce2b1a6d-e550-0410-aec6-3dcde31c8c00