Chrome 59 w/TurboFan is Sometimes Slower than 58

We recently upgraded our version of headless Chrome from 58 to 59 hoping for a 30% across-the-board reduction in CPU usage, but it wasn't so. This (contrived) benchmark shows a 38% decrease in performance for a React app rendering 100,000 divs.

	chrome 58	chrome 59
prerender.cloud (this site)	45ms	34ms	32% faster
create-react-app 100,000 hello-world divs	434ms	600ms	38% slower

Testing notes

• Actual test: ReactDOMServer.renderToString(<MyReactApp />)
• 2.5GHz Core-i7 MacBook Pro
• Chrome Headless versions 58.0.3028.2 and 59.0.3039.2
• took the average of 20-runs