LibSyntax: Teach each highlighter about it's comment syntax

Author: https://github.com/lanmonster 🔰
Commit: 31290c8527
Pull-request: https://github.com/SerenityOS/serenity/pull/15803
Reviewed-by: https://github.com/ADKaster ✅
Reviewed-by: https://github.com/Zaggy1024
Reviewed-by: https://github.com/idispatch

Userland/Libraries/LibWeb/CSS/SyntaxHighlighter/SyntaxHighlighter.h

@@ -19,6 +19,8 @@ public:
     virtual bool is_navigatable(u64) const override;
 
     virtual Syntax::Language language() const override { return Syntax::Language::CSS; }
+    virtual Optional<StringView> comment_prefix() const override { return "/*"sv; }
+    virtual Optional<StringView> comment_suffix() const override { return "*/"sv; }
     virtual void rehighlight(Palette const&) override;
 
 protected: