fix: correctly transform __proto__ properties

[ExE-Boss]

Q	A
Fixed Issues?	Fixes #4188 Fixes #11882 Fixes #12647
Patch: Bug Fix?	Yes
Major: Breaking Change?
Minor: New Feature?
Tests Added + Pass?	Yes
Documentation PR Link
Any Dependency Changes?
License	MIT

This fixes the transform of __proto__ to match the spec, where only the non‑computed, non‑shorthand form of __proto__ ({ __proto__: prototype }) is special. All other forms create an own enumerable __proto__ property.

To do:

• Add tests for when both @babel/plugin‑transform‑computed‑properties and @babel/plugin‑transform‑shorthand‑properties are used.
• Decide whether to treat { ["__proto__"]: anything } as special (always use [[Define]]) in setComputedProperties mode.

  • RESOLVED: Leave it as [[Set]] (fix: correctly transform __proto__ properties #12664 (comment))

    Decide whether to treat { ["__proto__"]: anything } as special (always use [[Define]]) in setComputedProperties mode.

    Imo we can leave it as [[Set]] and document it in the setComputedProperties docs

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[babel-bot]

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/37981/

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[nicolo-ribaudo]

Add tests for when both @babel/plugin‑transform‑computed‑properties and @babel/plugin‑transform‑shorthand‑properties are used.

This can be put either in one plugin or in the other, we don't have a general rule for choosing where to put cross-plugin tests.

Decide whether to treat { ["__proto__"]: anything } as special (always use [[Define]]) in setComputedProperties mode.

Imo we can leave it as [[Set]] and document it in the setComputedProperties docs

[nicolo-ribaudo]

Thanks!