[css-cascade] "Fetch an import" discards CSS URL modifiers

[AtkinsSJ]

"Fetch an import" step 3 says:

3. Let parsedUrl be the result of the URL parser steps with rule’s URL and parentStylesheet’s location. If the algorithm returns an error, return. [CSSOM]

The resulting parsedURL won't have any of the <request-url-modifier>s that the original @import's URL may have had, when it is then passed to "fetch a style resource".

It's also confusing that we parse the URL here, and then step 3 of "fetch a style resource" parses the URL again:

3. Let parsedUrl be the result of the URL parser steps with urlValue’s url and base. If the algorithm returns an error, return.

Maybe "fetch an import" step 3 is just redundant?

cc: @noamr

[weinig]

Dupe of #12086?

[AtkinsSJ]

Partly, yeah. I'll copy my comments to that issue.