To be compatible with safari we should not change the value on API
objects in Object.defineProperty (e.g., the window.location object).

Review URL: http://codereview.chromium.org/6673042

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@7169 ce2b1a6d-e550-0410-aec6-3dcde31c8c00