o = {};
          } else if (!model.hasOwnProperty(JSCompiler_renameProperty('__dataProto', model))) {
            model.__dataProto = Object.create(model.__dataProto);
          }
          model.__dataProto[property] = value;
        }
      }
    }
  }

  /**
   * Element class mixin that provides basic meta-programming for creating one
   * or more property accessors (getter/setter pair) that enqueue an async
   * (batched) `_propertiesChanged` callback.
   *
   * For basic usage of this mixin, simply d