fix(core): ensure stable webpack theme aliases sorting

[jrvidal]

Motivation

The comparison function provided for themes is not consistent. The resulting array order is implementation-dependent, which means it could break between Node releases (unlikely, though) or if somebody tried to run this code in a browser somehow 😬

Have you read the Contributing Guidelines on pull requests?

Yes

Test Plan

The only way to test this is by not using V8:

Before:

[
  '@theme/Navbar',
  '@theme/NavbarItem',
  '@theme/NavbarItem/DefaultNavbarItem',
].sort((a, b) => a.includes(`${b}/`) ? -1 : 0)

Chrome: ['@theme/Navbar', '@theme/NavbarItem/DefaultNavbarItem', '@theme/NavbarItem']
Firefox: [ "@theme/Navbar", "@theme/NavbarItem", "@theme/NavbarItem/DefaultNavbarItem"]

After:

[
  '@theme/Navbar',
  '@theme/NavbarItem',
  '@theme/NavbarItem/DefaultNavbarItem',
].sort((a, b) => a.includes(`${b}/`) ? -1 : (b.includes(`${a}/`) ? 1 : 0))

Chrome: ['@theme/Navbar', '@theme/NavbarItem/DefaultNavbarItem', '@theme/NavbarItem']
Firefox: [ "@theme/Navbar", "@theme/NavbarItem/DefaultNavbarItem", "@theme/NavbarItem" ]

Related PRs

Current implementation introduced here: #5383

[netlify]

✔️ [V2]
Built without sensitive environment variables

🔨 Explore the source changes: 8ae30b0

🔍 Inspect the deploy log: https://app.netlify.com/sites/docusaurus-2/deploys/6227dcc5dc718e0007aeb1f1

😎 Browse the preview: https://deploy-preview-6878--docusaurus-2.netlify.app

[github-actions]

⚡️ Lighthouse report for the changes in this PR:

Category	Score
🔴 Performance	48
🟢 Accessibility	100
🟠 Best practices	83
🟢 SEO	100
🟢 PWA	90

Lighthouse ran on https://deploy-preview-6878--docusaurus-2.netlify.app/

[Josh-Cena]

Oh, I didn't realize we are using 0! What if we just change 0 to 1? Could that ensure stable sorting?

[Josh-Cena]

I just re-parsed and understood where you are coming from 🤦‍♂️ Thanks a lot for catching that!