feat(plugin-legacy): support additionalModernPolyfills

[iammminzzy]

Description

This PR introduces additionalModernPolyfills option that mirrors the existing additionalLegacyPolyfills option.
The reason this is needed for the modern chunk is because due to #5142 the following is not actually true, and the only way to ensure polyfills are loaded before application code is to use plugin-legacy:

Note: if additional polyfills are needed for both the modern and legacy chunks, they can simply be imported in the application source code.

For example, this option can be used when an application only configures modernPolyfills but wishes to add custom polyfills for non-legacy browsers.

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[Shakeskeyboarde]

Can you explain what you mean when you say the existing docs are untrue? Why and in what case does importing polyfills in your source code not work?

[NMinhNguyen]

Can you explain what you mean when you say the existing docs are untrue? Why and in what case does importing polyfills in your source code not work?

Per the referenced issue, if you import a side-effectful module and you have chunking (e.g. in MPA mode), there’s no guarantee that it will run before other code that relies on that side effect to have executed.

[bluwy]

#5142 is about the bug in dev in prebundled dependencies. I think this issue is different?

But putting that issue aside and using the same arguments as the current additionalLegacyPolyfills option, this seems like a fine addition to me.

[NMinhNguyen]

#5142 is about the bug in dev in prebundled dependencies. I think this issue is different?

It might be rollup/rollup#3888 that I ran into (which also references #5142). But thanks for approving the PR, can’t wait to try it out 🙂

[patak-dev]

I think we could merge this one without going through a team meeting. It seems a non-controversial addition.

[NMinhNguyen]

@bluwy apologies for the direct ping, but when do you expect to publish a new version?

[bluwy]

I think as soon as after #16566 is merged, which is also plugin-legacy related.