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.

/**
 * Copyright (c) 2013-present Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @providesModule ReactART
 */
'use strict';
require('art/modes/current').setCurrent(
  require('art/modes/fast-noSideEffects') 
);
const Transform = require('art/core/transform');
const Mode = require('art/modes/current');
const React = require('React');
const ReactDOM = require('ReactDOM');
const ReactInstanceMap = require('ReactInstanceMap');
const ReactMultiChild = require('ReactMultiChild');
const ReactUpdates = require('ReactUpdates');
const emptyObject = require('emptyObject');
const invariant = require('invariant');
const assign = require('object-assign');
const pooledTransform = new Transform();
function childrenAsString(children) {