perf(compiler): remove object rest spread (BREAKING CHANGE)

[nolanlawson]

Details

Fixes #3577

Removes object rest spread transformation from the Babel transforms. This is only needed for browsers that don't support spread in object literals, which is well below our current minimum supported browser tier.

(Note that this PR will fail until #3648 is merged, due to Edge 18.)

Does this pull request introduce a breaking change?

• 🚨 Yes, it does introduce a breaking change.

This is mildly breaking because it is observable. In particular, if you have a counter inside of a getter and are relying on the count to report a particular number, then this change will break you because the Babel transform does not behave exactly like the native behavior. E.g.:

let count = 0;
const {
  foo: {
    bar,
    ...quux
  }
} = {
  get foo() {
    count++;
    return { bar: 42 };
  }
};
console.log(count); // Logs 2 for Babel, 1 for native

This is judged as extremely unlikely to break anyone, but it is technically a breaking change.

Does this pull request introduce an observable change?

• ⚠️ Yes, it does include an observable change.

See above.

GUS work item

W-13653003

[divmain]

LGTM. Really glad we can address issues like this with API versioning. Kudos!