An issue in Google Chrome preventing Lighthouse Experiments

Inspired by [WPT experiments](https://product.webpagetest.org/experiments), I tried to implement them for Lighthouse using puppeteer's request interception. It almost worked but there's a bug in Google Chrome: **requests interception API doesn't allow to return Gzip response**. [Here's the repo to reproduce it](https://github.com/Schniz/chrome-fulfill-request-issue). This bug breaks Lighthouse metrics significantly (100kb body response vs. 500kb degrades LH score).

I shared the bug with @paulirish he hinted it could be easily fixed. I hope that this issue brings awareness to this minor problem preventing Lighthouse Experiments.