@mapbox/mapbox-gl-style-spec references unbundled modules => build-time error

[elifitch]

When referencing modules that are not explicitly exported in /dist, as Studio does here and there to enable advanced features, I get a build-time error.

It looks like within.js is in fact referencing a data constant that is not bundled with the style spec package itself. https://github.com/mapbox/mapbox-gl-js/blob/master/src/style-spec/expression/definitions/within.js#L11

mapbox-gl-js version: 1.9.1

browser: N/A

Steps to Trigger Behavior

1. Import @mapbox/mapbox-gl-style-spec.
2. Attempt to reference the within expression definition.

Link to Demonstration

Creating an online example of this was difficult, but Mapbox Studio is a current one. Happy to work with y'all on replicating this behavior.

Expected Behavior

Possible to import modules from the src directory of @mapbox/mapbox-gl-style-spec.

Actual Behavior

Importing modules from the src directory of @mapbox/mapbox-gl-style-spec references files that are not bundled with the package.

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Posting here and tagging as release-blocker per advice from @arindam1993 🙇