Remove Factory::CopyMap(map) in favor of Map::Copy(map)

BUG=
R=ulan@chromium.org

Review URL: https://codereview.chromium.org/219963009

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@20411 ce2b1a6d-e550-0410-aec6-3dcde31c8c00