While in Mozilla disabling CORS is not that straightforward. One truly working option I've found was specific extension: CORS disabling extension for Mozilla Firefox: cors-everywhere.
In Opera there is several extension that can disable CROS for you : CORS-Toggle.
One can do it in Safari in 'Development' menu. Here is the screenshot with details:
To enable cross-domain requests in Internet Explorer 8, 9, 10 you should go even deeper - in Internet Options, then click Custom level button and find Miscellaneous block in the popup. Keep in mind the limitations of IE CORS implementation.
