Bump kMaxFastProperties (non-keyed assignments) to 128.

R=ishell@chromium.org

Review URL: https://codereview.chromium.org/238683004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@20754 ce2b1a6d-e550-0410-aec6-3dcde31c8c00