Update type annotations for login method (Closes #71)

Author: jakemac53

firebase-auth.html

@@ -198,8 +198,8 @@
      * is restored.
      *
      * @method login
-     * @param {string} params (optional)
-     * @param {string} options (optional)
+     * @param {Object} params (optional)
+     * @param {Object} options (optional)
      */
     login: function(params, options) {
       if (!this.ref || navigator.onLine === false) {