Allow defaults query in preset-env

[existentialism]

Q	A
Fixed Issues?	Fixes #7405
Patch: Bug Fix?	Y
Major: Breaking Change?	N
Minor: New Feature?	N
Tests Added + Pass?	Yes
Documentation PR Link
Any Dependency Changes?
License	MIT

[babel-bot]

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/9288/

[nicolo-ribaudo]

Is there a feature which shouldn't be transformed when using Browserlist's default target? If so, we could add it to the tests, to test the difference between "default targets" and "no targets"

[existentialism]

@nicolo-ribaudo part of the issue is, while we can handle usage of "defaults" when the query is passed directly as an option to the preset, if a user relies on browserslist to resolve the config (like via .browserslistrc or package.json) then our behavior of "no targets means the same as preset-latest" is difficult to do since we wont' be able to know whether the user didn't have targets or wants defaults.

For now, seems like just documenting this difference seems okay?

[danez]

I guess the best solution would be to check ourself if there is a browserlist config in the fs if there are not targets specified. We could do this with browserlist.findConfig(from). If we find one we do not change defaults. But that would also be a breaking change so I guess we would need to wait for v8. https://github.com/browserslist/browserslist/blob/master/node.js#L238

[nicolo-ribaudo]

I agree, we should do that in the next major release