Update to Drupal 8.0.0-beta15. For more information, see: https://www.drupal.org/node/2563023

core/modules/quickedit/js/models/BaseModel.js

@@ -15,8 +15,10 @@
      * @augments Backbone.Model
      *
      * @param {object} options
+     *   Options for the base model-
      *
      * @return {Drupal.quickedit.BaseModel}
+     *   A quickedit base model.
      */
     initialize: function (options) {
       this.__initialized = true;
@@ -24,12 +26,18 @@
     },
 
     /**
+     * Set a value on the model
      *
      * @param {object|string} key
+     *   The key to set a value for.
      * @param {*} val
+     *   The value to set.
      * @param {object} [options]
+     *   Options for the model.
      *
      * @return {*}
+     *   The result of `Backbone.Model.prototype.set` with the specified
+     *   parameters.
      */
     set: function (key, val, options) {
       if (this.__initialized) {