Appears to be working in Firefox but at least Chrome & Safari are broken. Should be a really recent regression so very few possible changes to blame...

Easiest repo: the todo list on our homepage.

topPlaying: 'playing',
  topProgress: 'progress',
  topRateChange: 'ratechange',
  topSeeked: 'seeked',
  topSeeking: 'seeking',
  topStalled: 'stalled',
  topSuspend: 'suspend',
  topTimeUpdate: 'timeupdate',
  topVolumeChange: 'volumechange',
  topWaiting: 'waiting',
};
function trapBubbledEventsLocal() {
  var inst = this;
  
  
  invariant(inst._rootNodeID, 'Must be mounted to trap events');
  var node = getNode(inst);
  invariant(
    node,
    'trapBubbledEvent(...): Requires node to be rendered.'
  );
  switch (inst._tag) {
    case 'iframe':
    case 'object':
      inst._wrapperState.listeners = [
        ReactBrowserEventEmitter.trapBubbledEvent(
          EventConstants.topLevelTypes.topLoad,
          'load',
          node
        ),