turbopack-css: demote recoverable CSS parse warnings to Warning severity (#91524)
### What?
Extends the CSS parse warning severity improvements in
`turbopack/crates/turbopack-css/src/process.rs`.
Canary (#90025, #91513) already:
- Added a `severity` field to `ParsingIssue` and a `fn severity()`
override
- Demoted `UnsupportedPseudoClass` / `UnsupportedPseudoElement` selector
errors from `Error` to `Warning`
- Still **silently dropped** all other unrecognized parser warning kinds
(`_ => { // Ignore }`)
This PR completes the work:
1. **Surfaces all previously-ignored parser warnings as
`IssueSeverity::Warning`** — the `_ => { // Ignore }` arm now emits a
`ParsingIssue` at `Warning` severity instead of discarding it.
2. **Refactors the warning loop** — the nested severity match inside the
existing `match err.kind` arm is replaced with a single top-level `let
severity = match err.kind { … }` followed by an unconditional emit. This
is cleaner and makes the severity logic easier to follow.
Hard parse/transform errors (`Err(e)` from `parse_css_stylesheet`,
minify errors, CSS module pure-selector errors) are unchanged — they
remain `IssueSeverity::Error`.
### Why?
Silently dropping parser warnings hides useful diagnostic information
from developers. Surfacing them as `Warning` gives visibility without
marking the build as broken.
The restructure also avoids a redundant
`UnsupportedPseudoClass`/`UnsupportedPseudoElement` check inside a
nested match — the top-level arm order (specific pseudo variants before
the catch-all `SelectorError(..)`) handles precedence correctly.
### How?
- Removed the now-unused `error::SelectorError` short import
(fully-qualified paths are used in the match).
- Replaced the `match err.kind { <arms that emit> … _ => { // Ignore }
}` pattern with:
1. `let severity = match err.kind { UnsupportedPseudo* => Warning, hard
errors => Error, _ => Warning };`
2. Unconditional `IssueSource` construction and `ParsingIssue {
severity, … }.emit()`.
Co-authored-by: Tobias Koppers <sokra@users.noreply.github.com>
Co-authored-by: Claude <noreply@anthropic.com>