Store i18n meta data in hidden symbols instead of js accessible properties

BUG=354967
LOG=N
TBR=jochen@chromium.org

Review URL: https://codereview.chromium.org/220673002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@20377 ce2b1a6d-e550-0410-aec6-3dcde31c8c00