Merged r18737 into 3.22 branch.

Fixed floor-of-div optimization.

BUG=334708
LOG=N
R=ulan@chromium.org

Review URL: https://codereview.chromium.org/146723002

git-svn-id: https://v8.googlecode.com/svn/branches/3.22@18820 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Merge remote-tracking branch 'upstream/3.22' into 3.22