Make all global private symbols own symbols.

R=arv@chromium.org, rossberg@chromium.org, wingo@igalia.com, yangguo@chromium.org

Review URL: https://codereview.chromium.org/486763002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23252 ce2b1a6d-e550-0410-aec6-3dcde31c8c00