Loading from out-of-range has to go to the runtime system to check if there
exists a property with that index in the prototype.

Review URL: http://codereview.chromium.org/3410011

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5471 ce2b1a6d-e550-0410-aec6-3dcde31c8c00