SyntaxError is reported in strict mode when deleting
an unqualified identifier. (11.4.1 of Ecma-262 5th ed)

Review URL: http://codereview.chromium.org/6516003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6780 ce2b1a6d-e550-0410-aec6-3dcde31c8c00