code: function _getOrigin(event){
          if (event.origin) {
              // This is the HTML5 property
              return getLocation(event.origin);
          }
          if (event.uri) {
              // From earlier implementations 
              return getLocation(event.uri);
          }
          if (event.domain) {
              // This is the last option and will fail if the 
              // origin is not using the same schema as we are
              return location.protocol + "//" + event.domain;
          }
          throw "Unable to retrieve the origin of the event";
      }
docs: the domain to communicate with 
  Resolves the origin from the event object
  @private
  @param {Object} event The messageevent
  @return {String} The scheme, host and port of the origin