Let's automatically test paulirish/what-forces-layout.md.

If the build fails this either means something is wrong or some tests don't yield the expected results.

This is a work-in-progress feel free to add more tests.

The Idea is to setup a testcase for each of the actions described (preferably a self-contained .html file). Puppeteer puppeteer/puppeteer opens runs the tests and reports the amount of style recalculations. Furthermore performance-timelines are stored as JSON-Files - therefore they can be parsed and analyzed (Chrome Debugger).