Only create arguments-maps in the bootstrapper, remove now obsolete ValueType flag.

TBR=dslomov@chromium.org

BUG=

Review URL: https://codereview.chromium.org/375503008

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22245 ce2b1a6d-e550-0410-aec6-3dcde31c8c00