Revert "Drop broken and unnecessary RequiredInputRepresentation() in HMathFloorOfDiv."

This reverts r16190.

TBR=danno@chromium.org

Review URL: https://codereview.chromium.org/23188003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@16191 ce2b1a6d-e550-0410-aec6-3dcde31c8c00