chore(babel): Remove preset-env excludes and do not configure them separately

[dac09]

Context
We originally had the excludes block in preset-env - because it was printing warnings when building with babel/webpack 4 (way back when) - see the comment in the removed code for a link to the issue.

So the solution was to exclude it from preset-env, and include it as a separate plugin.

I don't think we need to do this anymore - and seems to work fine with project:copy. But I'm not a 100% sure its all OK until we merge into canary.

[Tobbe]

With this change we'll now get the default behavior of loose: false, right? Do you know exactly why we had loose: true?

[dac09]

With this change we'll now get the default behavior of loose: false, right? Do you know exactly why we had loose: true?

Yeah it was a webpack 4 thing. webpack/webpack#9708

[Tobbe]

The linked issue doesn't mention "loose" anywhere. The linked issue seems to be more about why we include these, and then exclude them later

Reading the babel docs however it says

When true, private methods will be assigned directly on its parent via Object.defineProperty rather than a WeakSet. This results in improved performance and debugging

[dac09]

I did this change Tobbe, so I remember.

[dac09]

lol I'm actually not sure about loose anymore. This is the old PR #2554 - but trying to find one where loose was enabled.