The error event on `<source>` elements doesn't work. Looking at #4370, it seems like there is an `onError` for `<video>` but I can't tell if that's supposed to work for `<source>` too.

The error event is useful so I can deduce which format the browser is using.

);
    if (this._tag === 'select') {
      
      
      transaction.getReactMountReady().enqueue(postUpdateSelectWrapper, this);
    }
  },
  /**
   * Reconciles the properties by detecting differences in property values and
   * updating the DOM as necessary. This function is probably the single most
   * critical path for performance optimization.
   *
   * TODO: Benchmark whether checking for changed values in memory actually
   *       improves performance (especially statically positioned elements).
   * TODO: Benchmark the effects of putting this at the top since 99% of props
   *       do not change for a given reconciliation.
   * TODO: Benchmark areas that can be improved with caching.
   *
   * @private
   * @param {object} lastProps
   * @param {object} nextProps
   * @param {?DOMElement} node
   */
  _updateDOMProperties: function(lastProps, nextProps, transaction) {
    var propKey;
    var styleName;
    var styleUpdates;
    for (propKey in lastProps) {
      if (nextProps.hasOwnProperty(propKey) ||
         !lastProps.hasOwnProperty(propKey) ||