`scrollLeft` returns decimal values in firefox

[Janpot]

Describe the bug

Since 4.0.14, we see decimal values for scrollLeft in firefox

- Expected
+ Received

- 200
+ 200.35000610351562

 ❯ test/basic.test.ts:21:34
     19| 
     20|   container.scrollLeft = 200;
     21|   expect(container.scrollLeft).to.equal(200);
       |                                  ^
     22| });
     23| 

doesn't happen in other browsers, doesn't happen in 4.0.13.

Bifurcated with pkg.pr.new and it seems to originate in 64502a2 (or the parent commit, CI completely failed for that one)

Reproduction

See https://github.com/Janpot/vitest-repro-scroll

System Info

System:
    OS: macOS 14.6.1
    CPU: (8) arm64 Apple M1
    Memory: 60.77 MB / 16.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 24.7.0 - ~/.nvm/versions/node/v24.7.0/bin/node
    npm: 11.5.1 - ~/.nvm/versions/node/v24.7.0/bin/npm
    pnpm: 10.13.1 - ~/.nvm/versions/node/v24.7.0/bin/pnpm
  Browsers:
    Safari: 17.6
  npmPackages:
    @vitest/browser-playwright: latest => 4.0.15 
    @vitest/ui: latest => 4.0.15 
    playwright: 1.57.0 => 1.57.0 
    vite: latest => 7.2.7 
    vitest: latest => 4.0.15

Used Package Manager

pnpm

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