operty using `dash-case`-to-`camelCase` convention.
   *
   * @polymerMixin
   * @memberof Polymer
   * @summary Element class mixin for reacting to property changes from
   *   generated property accessors.
   */
  Polymer.PropertyAccessors = Polymer.dedupingMixin(superClass => {

    /**
     * @polymerMixinClass
     * @implements {Polymer_PropertyAccessors}
     * @unrestricted
     */
    class PropertyAccessors extends superClass {

      /**
       * Generates property accessors for all attributes in