code: function getProperty(url, prefName) {
    var sbs = Cc["@mozilla.org/intl/stringbundle;1"]
              .getService(Ci.nsIStringBundleService);
    var bundle = sbs.createBundle(url);
  
    try {
      return bundle.GetStringFromName(prefName);
    } catch (ex) {
      throw new Error(arguments.callee.name + ": Unknown property - " + prefName);
    }
  }
docs: Returns the value of an individual property.
  
  @param {string} url
  URL of the string bundle.
  @param {string} prefName
  The property to get the value of.
  
  @return The value of the requested property
  @type string