Add declaration of state method of $location service.
The documentation of the state method is here:
https://docs.angularjs.org/api/ng/service/$location#state
and here's the source code:
@@ -1898,6 +1898,12 @@ angular.$location.prototype.replace = function() {};
*/
angular.$location.prototype.search = function(opt_search, opt_paramValue) {};
+/**
+ * @param {Object=} opt_state
+ * @return {(!Object|!angular.$location)}
+ */
+angular.$location.prototype.state = function(opt_state) {};
+
/**
* @param {string=} opt_url
* @return {string}
