test: fix parallel/test-repl-harmony with new v8

Assignment to a const var in strict mode is a lazy TypeError now.
Update the test accordingly.

PR-URL: https://github.com/iojs/io.js/pull/243


Reviewed-By: Fedor Indutny <fedor@indutny.com>
Reviewed-By: Trevor Norris <trev.norris@gmail.com>