breaking: remove Node polyfills (and by extension support for Node 18)

[Rich-Harris]

Vercel supports Node 20 and 22. These versions expose File and crypto to the global scope, which therefore no longer need to be polyfilled.

Marked as a major version because it's technically a breaking change, but not really since you already can't use Node 18 on Vercel.

---

Please don't delete this checklist! Before submitting the PR, please make sure you do the following:

• It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs
• This message body should clearly illustrate what problems it solves.
• Ideally, include a test that fails without this PR but passes with it.

Tests

• Run the tests with pnpm test and lint the project with pnpm lint and pnpm check

Changesets

• If your PR makes a change that should be noted in one or more packages' changelogs, generate a changeset by running pnpm changeset and following the prompts. Changesets that add features should be minor and those that fix bugs should be patch. Please prefix changeset messages with feat:, fix:, or chore:.

Edits

• Please ensure that 'Allow edits from maintainers' is checked. PRs without this option may be closed.

[changeset-bot]

🦋 Changeset detected

Latest commit: 47f9561

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@sveltejs/adapter-vercel	Major

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[teemingc]

We should probably remove references to Node.js 18 too:

1. kit/packages/adapter-vercel/index.js

   Line 35 in 9c933a2

   if (major < 18 || major > 22) {

2. kit/packages/adapter-vercel/index.js

   Line 37 in 9c933a2

   `Building locally with unsupported Node.js version: ${process.version}. Please use Node 18, 20 or 22 to build your project, or explicitly specify a runtime in your adapter configuration.`

3. kit/packages/adapter-vercel/index.js

   Line 308 in 9c933a2

   if (runtime !== 'edge' && (!node_runtime || parseInt(node_runtime[1]) < 18)) {

4. kit/packages/adapter-vercel/index.js

   Line 310 in 9c933a2

   `Invalid runtime '${runtime}' for route ${route.id}. Valid runtimes are 'edge' and 'nodejs18.x' or higher ` +

5. kit/documentation/docs/25-build-and-deploy/90-adapter-vercel.md

   Line 45 in 9c933a2

   - `runtime`: `'edge'`, `'nodejs18.x'`, `'nodejs20.x'` or `'nodejs22.x'`. By default, the adapter will select the `'nodejs<version>.x'` corresponding to the Node version your project is configured to use on the Vercel dashboard

[Rich-Harris]

good catch, done

[svelte-docs-bot]

Preview: https://svelte-dev-git-preview-kit-14732-svelte.vercel.app/

[teemingc]

Thanks! Note that we need to update the Vercel adapter major in adapter-auto before we create a new release so that it installs the new major

kit/packages/adapter-auto/adapters.js

Line 10 in dedda71

version: '5'