Also fix an awfull bug in simplified lowering.

TEST=cctest,mjsunit/asm
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/640603003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24463 ce2b1a6d-e550-0410-aec6-3dcde31c8c00