Before https://github.com/facebook/react/pull/14917, I used to get this:

<img width="502" alt="screen shot 2019-02-21 at 5 38 03 pm" src="https://user-images.githubusercontent.com/810438/53190100-cbe20d00-3600-11e9-9ffa-b230f3bb78fe.png">

#!/usr/bin/env node
'use strict';
const {join} = require('path');
const puppeteer = require('puppeteer');
const theme = require('../theme');
const {logPromise} = require('../utils');
const validate = async ({cwd}) => {
  const browser = await puppeteer.launch();
  const page = await browser.newPage();
  await page.goto(
    'file://' + join(cwd, 'fixtures/tracing/index.html?puppeteer=true')
  );
  try {
    return await page.evaluate(() => {