[andrewiggins]

Summary

@remote-dom/polyfill was the last project in this repo that didn't support erasableSyntaxOnly without exceptions. This PR removes those exceptions.

It turns out that our babel transform turned these const enums into full TS enums even though we didn't use them as such. These data structures cost us 1.5kb in a minified build. So I've replaced the const enums with just const variables. These enums were never exported publically so it shouldn't be a breaking change. It also more closely matches the DOM which just uses raw numbers here anyway.

What changed

• replace the Polyfill's TypeScript parameter property with an explicit field assignment
• replace five const enum declarations with erasable scalar constants
• preserve publicly reachable numeric fields as number and namespace values as a string-literal union
• add coverage for observable event, node type, and namespace behavior
• add a patch changeset for @remote-dom/polyfill

Every TypeScript project now enables erasableSyntaxOnly without syntax-related suppression comments.

ESM bundle size

Measured by bundling and minifying the public Window export with esbuild 0.25.12:

Metric	Before	After	Change
Minified	22,282 B	20,742 B	-1,540 B
Gzip	7,516 B	7,167 B	-349 B
Brotli	6,710 B	6,383 B	-327 B

Testing

• pnpm exec tsc --build --pretty --force
• pnpm exec vitest run
• pnpm build
• pnpm lint
• pnpm exec playwright test --workers=1
• direct execution of the Polyfill source with Node type stripping