when transforming from slow to fast-case array elements.

This fixes issue 201:
  
   http://code.google.com/p/v8/issues/detail?id=201
   
Review URL: http://codereview.chromium.org/18711

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1135 ce2b1a6d-e550-0410-aec6-3dcde31c8c00