For keyed IC's the name is not necessarily a string.

BUG=http://crbug.com/37853
TEST=test/mjsunit/regress/regress-crbug-37853.js
Review URL: http://codereview.chromium.org/872001

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4094 ce2b1a6d-e550-0410-aec6-3dcde31c8c00