fix(css): handle environment with browser globals

[bluwy]

Description

When running sass in an environment that has browser globals, e.g. jsdom, it trips up when trying to absolute-ify file paths sass/dart-sass#710

As location.href is shimmed as http://localhost/, the file path sass might absolute-ify to would look something like: http://localhost/Users/bjorn/project/foo/bar.scss.

This PR handles this edge case by stripping it, and also tries to avoid internal sass errors when reading file from the fs by reading it ourselves.

Fixes withastro/astro#5456
Fixes vitest-dev/vitest#1230

Additional context

Astro shims globals by default. I'm probably on the side that we shouldn't do it, but since this helps Vitest too it might be worth fixing here first.

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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[nrayburn-tech]

Does this work when using a location that isn’t just “http://localhost”?
Like a reconfigured jsdom instance, https://stackoverflow.com/a/65741127/13168665.

[sapphi-red]

FYI when navigator is shimmed (globalThis.navigator = {}), sass crashes. (#5815 (comment))
This is not directly related to this PR, but just in case you hit this in future.

[sapphi-red]

Let me confirm that my understanding is correct just to be sure. Here's what I understand:

• sass's own importer only resolves relative path. relative paths are correctly resolved by sass's own importer even if window/location exists.
• here Vite's custom importer handles non-relative path and resolves to an absolute path. absolute paths will be broken by sass so we need to load the content on our side.

[bluwy]

Yup that's exactly what happens right now 👍

[bluwy]

Does this work when using a location that isn’t just “http://localhost”?
Like a reconfigured jsdom instance, https://stackoverflow.com/a/65741127/13168665.

I didn't know it can be reconfigured that way. In that case it makes sense to support that edge case too then.