act as if they have no properties in their prototype chains.

This fixes V8 issue 193:

  http://code.google.com/p/v8/issues/detail?id=193.
Review URL: http://codereview.chromium.org/18709

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1132 ce2b1a6d-e550-0410-aec6-3dcde31c8c00