Tag all prototypes as proto, except those set using __proto__

BUG=
R=ishell@chromium.org, yangguo@chromium.org

Review URL: https://codereview.chromium.org/450303003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23042 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Small clean up of externalizing strings.

R=verwaest@chromium.org

Review URL: https://codereview.chromium.org/462643002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23043 ce2b1a6d-e550-0410-aec6-3dcde31c8c00