We missed this because Flow wasn't being run properly on Travis but now that it is, it's clear that #7716 introduced a bunch of new Flow failures. Most of these shouldn't be too bad and I like to say "you break it you buy it" so this one is for you @Aweary :)

There were a couple other pre-existing Flow issues that @vjeux is going to fix, so mostly this should just be the TestRenderer issues.

if (props.visible == null || props.visible) {
        node.show();
      } else {
        node.hide();
      }
    }
    for (let type in EventTypes) {
      this.putEventListener(EventTypes[type], props[type]);
    }
  },
  mountComponentIntoNode: function(rootID, container) {
    throw new Error(
      'You cannot render an ART component standalone. ' +
      'You need to wrap it in a Surface.'
    );
  }
};
const Group = createComponent('Group', NodeMixin, ContainerMixin, {
  mountComponent: function(
    transaction,
    nativeParent,
    nativeContainerInfo,
    context
  ) {
    this.node = Mode.Group();
    const props = this._currentElement.props;
    this.applyGroupProps(emptyObject, props);
    this.mountAndInjectChildren(props.children, transaction, context);
    return this.node;
  },