Hydrogen should optimize not only SMI clauses, but clauses with string literals
too.

Patch from fedor.indutny <fedor.indutny@gmail.com>.

R=vegorov@chromium.org
BUG=
TEST=
Review URL: http://codereview.chromium.org/8373029

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9901 ce2b1a6d-e550-0410-aec6-3dcde31c8c00