Suggestion: Don't collect code coverage from registerServiceWorker.js File

[wirmar]

Currently coverage is collected for the registerServiceWorker.js File by default. However this code was not user generated. Maybe this File should be ignored by default? ("collectCoverageFrom": ["src/**/*.{js,jsx}", "!**/registerServiceWorker.js"])

[gaearon]

I don't know. I think it's a slippery slope: src/index.js was also generated and also not covered. And I think it's fine. Chasing 100% coverage is usually a misleading goal, and I don't want to give people the feeling that we encourage that.