src: disable harmony object literals

Per the discussion in https://github.com/iojs/io.js/pull/272, upstream
V8 has disabled Harmony object literals for the time being.  Do the
same for feature parity.

PR-URL: https://github.com/iojs/io.js/pull/272


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Domenic Denicola <domenic@domenicdenicola.com>