v0.34.2 breaks web workers when not using jsdom

[marvinruder]

Describe the bug

Given that vitest is run without an environment like jsdom (i.e. the test.environment config attribute is unset), when importing a worker using the syntax import MyWorker from '../src/worker?worker' and creating an instance of this worker using new MyWorker(), then tests fail with the following stack trace:

 FAIL  test/init.test.ts > simple worker
ReferenceError: self is not defined
 ❯ getFileIdFromUrl ../../packages/web-worker/dist/pure.js:347:24
 ❯ new Worker ../../packages/web-worker/dist/pure.js:408:18
 ❯ new WorkerWrapper src/worker.ts:2:18
      1| self.onmessage = (e) => {
      2|   self.postMessage(`${e.data} world`)
       |                  ^
      3| }
      4| 
 ❯ test/init.test.ts:37:20

Note that @vitest/web-workers explicitly states in their README that jsdom is not required:

vitest/packages/web-worker/README.md

Line 3 in 41e828f

> Web Worker support for Vitest testing. Doesn't require JSDom.

Reproduction

https://github.com/marvinruder/vitest

1. Open Repository in GitHub Codespace
2. Run pnpm install --frozen-lockfile
3. Run pnpm build
4. Run cd test/web-worker
5. Run pnpm test and observe that many tests fail, e.g. test/init.test.ts > simple worker

System Info

System:
    OS: Linux 5.15 Ubuntu 20.04.6 LTS (Focal Fossa)
    CPU: (2) x64 Intel(R) Xeon(R) Platinum 8272CL CPU @ 2.60GHz
    Memory: 2.21 GB / 3.82 GB
    Container: Yes
    Shell: 5.0.17 - /bin/bash
  Binaries:
    Node: 20.5.0 - ~/nvm/current/bin/node
    Yarn: 1.22.19 - /usr/bin/yarn
    npm: 9.8.0 - ~/nvm/current/bin/npm
    pnpm: 8.6.6 - /workspaces/vitest/node_modules/.bin/pnpm
  npmPackages:
    @vitest/browser: workspace:* => 0.34.2 
    @vitest/coverage-istanbul: workspace:* => 0.34.2 
    @vitest/coverage-v8: workspace:* => 0.34.2 
    @vitest/ui: workspace:* => 0.34.2 
    vite: ^4.2.1 => 4.3.9 
    vitest: workspace:* => 0.34.2

Used Package Manager

pnpm

Validations

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• Read the Contributing Guidelines.
• Read the docs.
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• The provided reproduction is a minimal reproducible example of the bug.

[marvinruder]

Introduced in #3950