@babel/preset-env: `DEBUG` option

Using targets:
{
  "chrome": "71"
}

Using modules transform: auto

Using plugins:
  syntax-async-generators { "chrome":"71" }
  syntax-object-rest-spread { "chrome":"71" }
  syntax-json-strings { "chrome":"71" }
  syntax-optional-catch-binding { "chrome":"71" }

Using polyfills with `usage` option:

[<CWD>/src/in.js] Added following core-js polyfills:
  esnext.map.delete-all { "chrome":"71" }
  esnext.map.every { "chrome":"71" }
  esnext.map.filter { "chrome":"71" }
  esnext.map.find { "chrome":"71" }
  esnext.map.find-key { "chrome":"71" }
  esnext.map.includes { "chrome":"71" }
  esnext.map.key-of { "chrome":"71" }
  esnext.map.map-keys { "chrome":"71" }
  esnext.map.map-values { "chrome":"71" }
  esnext.map.merge { "chrome":"71" }
  esnext.map.reduce { "chrome":"71" }
  esnext.map.some { "chrome":"71" }
  esnext.map.update { "chrome":"71" }
  esnext.observable { "chrome":"71" }
  esnext.symbol.observable { "chrome":"71" }

[<CWD>/src/in2.js] Based on your code and targets, core-js polyfills were not added.
Successfully compiled 2 files with Babel.