Go into slow case when encountering object initialization on the top level to optimize performance of code like
C.prototype.x = ...;
C.prototype.y = ...;
...
C.prototype.z = ...;
Review URL: http://codereview.chromium.org/27128

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1372 ce2b1a6d-e550-0410-aec6-3dcde31c8c00