setState = function(state) {
    if (state == self.LOADING || self.readyState !== state) {
      self.readyState = state;

      if (settings.async || self.readyState < self.OPENED || self.readyState === self.DONE) {
        self.dispatchEvent("readystatechange");
      }

      if (self.readyState === self.DONE && !errorFlag) {
        self.dispatchEvent("load");
        // @TODO figure out InspectorInstrumentation::didLoadXHR(cookie)
        self.dispatchEvent("loadend");
      }
    }
  }
Changes readyState and calls onreadystatechange.

@param int state New state