R=jkummerow@chromium.org
TEST=mjsunit/math-floor-part2

Review URL: https://codereview.chromium.org/15743005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14752 ce2b1a6d-e550-0410-aec6-3dcde31c8c00