Zap prototype transitions in release mode, too.

R=ulan@chromium.org
BUG=431559
LOG=n

Review URL: https://codereview.chromium.org/715233002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25287 ce2b1a6d-e550-0410-aec6-3dcde31c8c00