Drop parenthesis about alternative design in non-normative section

As suggested by Hans.

chapters/classes.tex

@@ -601,8 +601,6 @@ \subsection{Parameters}\label{parameters}
   b = n > 3;
 \end{lstlisting}
 Here, a good error message for the variability error can include the information that the reason for \lstinline!n! being a non-evaluable parameter is that it has a dependency on the non-evaluable parameter \lstinline!b!.
-
-(Would evaluable and non-evaluable parameters have had different variability prefixes in their component declarations, it would have been possible to detect and report errors directly at the evaluable component declarations instead.)
 \end{nonnormative}
 
 \begin{nonnormative}