Don't look for babelrc file during test

[nhajidin]

Fixes #949

[fson]

Thanks for the pull request @nhajidin! Can you describe the steps you followed to check that this works correctly?

[nhajidin]

I did the following:

1. Run create-react-app issue-949
2. Add a .babelrc file with { "presets": ["es2015"] }
3. Run cd issue-949
4. Run npm test; the test will fail
5. Edit file node_modules\react-scripts\config\jest\transform.js to include babelrc: false
6. Run npm test; the test will now pass

[fson]

Thanks!