style: Remove layout.css.is-and-where-better-error-recovery.enabled

We shipped this in 84

Differential Revision: https://phabricator.services.mozilla.com/D123623

components/selectors/parser.rs

@@ -256,11 +256,6 @@ pub trait Parser<'i> {
         false
     }
 
-    /// The error recovery that selector lists inside :is() and :where() have.
-    fn is_and_where_error_recovery(&self) -> ParseErrorRecovery {
-        ParseErrorRecovery::IgnoreInvalidSelector
-    }
-
     /// Whether the given function name is an alias for the `:is()` function.
     fn is_is_alias(&self, _name: &str) -> bool {
         false
@@ -344,7 +339,7 @@ pub struct SelectorList<Impl: SelectorImpl>(
 );
 
 /// How to treat invalid selectors in a selector list.
-pub enum ParseErrorRecovery {
+enum ParseErrorRecovery {
     /// Discard the entire selector list, this is the default behavior for
     /// almost all of CSS.
     DiscardList,
@@ -2277,7 +2272,7 @@ where
         state |
             SelectorParsingState::SKIP_DEFAULT_NAMESPACE |
             SelectorParsingState::DISALLOW_PSEUDOS,
-        parser.is_and_where_error_recovery(),
+        ParseErrorRecovery::IgnoreInvalidSelector,
     )?;
     Ok(component(inner.0.into_vec().into_boxed_slice()))
 }
@@ -2686,10 +2681,6 @@ pub mod tests {
             true
         }
 
-        fn is_and_where_error_recovery(&self) -> ParseErrorRecovery {
-            ParseErrorRecovery::DiscardList
-        }
-
         fn parse_part(&self) -> bool {
             true
         }
@@ -3294,9 +3285,9 @@ pub mod tests {
         assert!(parse("::slotted(div)::before").is_ok());
         assert!(parse("slot::slotted(div,foo)").is_err());
 
-        assert!(parse("foo:where()").is_err());
+        assert!(parse("foo:where()").is_ok());
         assert!(parse("foo:where(div, foo, .bar baz)").is_ok());
-        assert!(parse("foo:where(::before)").is_err());
+        assert!(parse_expected("foo:where(::before)", Some("foo:where()")).is_ok());
     }
 
     #[test]

components/style/gecko/selector_parser.rs

@@ -14,7 +14,7 @@ use crate::string_cache::{Atom, Namespace, WeakAtom, WeakNamespace};
 use crate::values::{AtomIdent, AtomString};
 use cssparser::{BasicParseError, BasicParseErrorKind, Parser};
 use cssparser::{CowRcStr, SourceLocation, ToCss, Token};
-use selectors::parser::{ParseErrorRecovery, SelectorParseErrorKind};
+use selectors::parser::SelectorParseErrorKind;
 use selectors::SelectorList;
 use std::fmt;
 use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss as ToCss_};
@@ -311,15 +311,6 @@ impl<'a, 'i> ::selectors::Parser<'i> for SelectorParser<'a> {
         true
     }
 
-    #[inline]
-    fn is_and_where_error_recovery(&self) -> ParseErrorRecovery {
-        if static_prefs::pref!("layout.css.is-and-where-better-error-recovery.enabled") {
-            ParseErrorRecovery::IgnoreInvalidSelector
-        } else {
-            ParseErrorRecovery::DiscardList
-        }
-    }
-
     #[inline]
     fn parse_part(&self) -> bool {
         true