LibJS: Remove Value::to_deprecated_string_without_side_effects

Author: https://github.com/trflynn89
Commit: ba40ef1f3a
Pull-request: https://github.com/SerenityOS/serenity/pull/17461
Reviewed-by: https://github.com/linusg

Userland/Libraries/LibJS/Runtime/Value.h

@@ -395,7 +395,6 @@ public:
     ThrowCompletionOr<FunctionObject*> get_method(VM&, PropertyKey const&) const;
 
     ErrorOr<String> to_string_without_side_effects() const;
-    DeprecatedString to_deprecated_string_without_side_effects() const;
 
     Value value_or(Value fallback) const
     {