Re-enable serialization under harmony-scoping.

R=yangguo@chromium.org
BUG=v8:3689
LOG=N

Review URL: https://codereview.chromium.org/717153002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25294 ce2b1a6d-e550-0410-aec6-3dcde31c8c00