The codebase was incredibly inconsistent with the use of spacing around
curly braces, e.g.:
```
// this?
const a = {b: 1}
// or?
const a = { b: 1 }
```
This extended into import statements also. Google's styleguide is no
spacing, so we're going with that.
This patch:
- updates `utils/fetch_devices.js` script to format UAs for Chrome UAs
and to add iPhone 6/7/8 as separate devices.
- re-generates `DeviceDescriptors.js` with the new script
Fixes#2730.
This patch converts lib/DevicesDescriptors from a devtools front-end
format into a puppeteer format.
This patch does this via introducing a scripts utils/fetch_devices.js
which grabs devices from upstream of DevTools Front-end and
converts them into puppeteer devices.
References #88.
