LibJS: Remove unused CodeGenerationError::to_deprecated_string

Userland/Libraries/LibJS/Bytecode/CodeGenerationError.h

@@ -18,7 +18,6 @@ struct CodeGenerationError {
     StringView reason_literal;
 
     ErrorOr<String> to_string() const;
-    DeprecatedString to_deprecated_string();
 };
 
 template<typename T>

Userland/Libraries/LibJS/Bytecode/Generator.cpp

@@ -326,9 +326,4 @@ Label Generator::perform_needed_unwinds_for_labelled_continue_and_return_target_
     VERIFY_NOT_REACHED();
 }
 
-DeprecatedString CodeGenerationError::to_deprecated_string()
-{
-    return DeprecatedString::formatted("CodeGenerationError in {}: {}", failing_node ? failing_node->class_name() : "<unknown node>", reason_literal);
-}
-
 }