ng for objects/arrays.
   *
   * In order to make the dirty check strategy configurable, see
   * `Polymer.OptionalMutableDataBehavior`.
   *
   * Note, the performance characteristics of propagating large object graphs
   * will be worse as opposed to using strict dirty checking with immutable
   * patterns or Polymer's path notification API.
   *
   * @polymerBehavior
   * @memberof Polymer
   * @summary Behavior to skip strict dirty-checking for objects and
   *   arrays
   */
  Polymer.MutableDataBehavi