LibWeb: Implement the :volume-locked pseudo-class

Author: https://github.com/AtkinsSJ
Commit: eb7cda1172
Pull-request: https://github.com/SerenityOS/serenity/pull/20302
Reviewed-by: https://github.com/trflynn89 ✅

Userland/Libraries/LibWeb/CSS/Selector.cpp

@@ -235,6 +235,7 @@ ErrorOr<String> Selector::SimpleSelector::serialize() const
         case Selector::SimpleSelector::PseudoClass::Type::Paused:
         case Selector::SimpleSelector::PseudoClass::Type::Seeking:
         case Selector::SimpleSelector::PseudoClass::Type::Muted:
+        case Selector::SimpleSelector::PseudoClass::Type::VolumeLocked:
             // If the pseudo-class does not accept arguments append ":" (U+003A), followed by the name of the pseudo-class, to s.
             TRY(s.try_append(':'));
             TRY(s.try_append(pseudo_class_name(pseudo_class.type)));