Runtime_DefineOrRedfineAccessorProperty basically does the same, so we have 1
code path less to worry about.

Review URL: https://chromiumcodereview.appspot.com/9424033

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10779 ce2b1a6d-e550-0410-aec6-3dcde31c8c00