Also refactor the related code in preparation for fixing the
range analysis.

BUG=v8:3204
LOG=y
R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/190713002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19737 ce2b1a6d-e550-0410-aec6-3dcde31c8c00