hotfix: revert to corejs@2

[pi0]

Revert core-js to v2 as it is the default for current babel and forcing to v3 causes issues like #5313. Upgrading is also a breaking change for projects that have a babel.config file. So it makes sense to do it for nuxt3 or when ecosystem adopted more to v3.

[codecov-io]

Codecov Report

Merging #5317 into dev will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##              dev    #5317   +/-   ##
=======================================
  Coverage   95.66%   95.66%           
=======================================
  Files          74       74           
  Lines        2513     2513           
  Branches      639      639           
=======================================
  Hits         2404     2404           
  Misses         92       92           
  Partials       17       17

Impacted Files	Coverage Δ
packages/webpack/src/config/base.js	95.5% <ø> (ø)	⬆️
packages/babel-preset-app/src/index.js	100% <100%> (ø)	⬆️

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[clarkdo]

LGTM

[clarkdo]

One thing need to be noticed, if any lib has already updated to core-js 3, this is still an issue.

So it would be better to provide a way to detect or manually config corejs version, I'll work on it, for now let's revert and release this pr as hotfix.

[simllll]

just ran into this issue, we adopted already everything to core js 3.. actually I was just waiting for 2.5 to come because of core js 3. Any other idea how we could solve this?

[pi0]

@simllll sorry to hear that :( Actually we've faced lots of problems because of libs that implicitly depend on corejs 2 and we can't support both at a same time. How did you get prepared for 3.x?

[simllll]

Yeah we had similar troubles, but switched or patched some libraries to get over it. Wasn't that much effort in the end for us, but still not so cool if we would revert this now.

I just read clarkdos comment that he is working on a option/flag to set the core is version, this would solve our problem! So I just fixed our version to 2.5.0 for now.

[pi0]

@simllll You requested and it will be possible with next version (2.6.0) via #5411. All thanks to @clarkdo ❤️

[simllll]

Very nice :) thanks guys for this awesome project!