* refactor: simply browserslists defaults overwriting
When `hasTargets` is `false`, `targets` is always an empty object by definition, `objectToBrowserslist({})` always return `[]` therefore we can remove `objectToBrowserslist`.
* test: apply external-helpers on preset-env test fixtures
* test: add ie 6 to force all transforms in corejs 3, debug, corejs 2 fixtures
* Add ie 6 as targets for test fixtures
* add plugins
* add plugin description
* run build-data
* set shipped proposals true
* update test fixtures
* corejs.proposals should not imply shipped proposals
* fix eslint errors
Please enter the commit message for your changes. Lines starting
* create new object in packages/babel-compat-data/scripts/data/plugin-features.js
While it isn't technically needed because regenerator already handles
async functions, it doesn't play well with the Promise detection logic
used by @babel/preset-env's useBuiltIns and @babel/transform-runtime.
The plugin exclusion logic isn't removed, because
1) it will be useful when merging @babel/preset-modules
into @babel/preset-env
2) if/when regenerator will support injecting a custom promise,
we can enable this optimization again
