Replace HCheckPrototypeMaps by explicit map checks of constant values.

R=danno@chromium.org

Review URL: https://chromiumcodereview.appspot.com/21065006

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@16055 ce2b1a6d-e550-0410-aec6-3dcde31c8c00