Use the syntax of a property addition as a hint for controlling the fast-mode vs. dictionary mode heursitics on objects.
Review URL: https://chromiumcodereview.appspot.com/10537050

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11732 ce2b1a6d-e550-0410-aec6-3dcde31c8c00