R=ulan@chromium.org
TEST=preparser/duplicate-property,mjsunit/regress/regress-parse-object-literal

Review URL: https://codereview.chromium.org/26375004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@17136 ce2b1a6d-e550-0410-aec6-3dcde31c8c00