Correct example in section about super-bounded types

Author: eernstg

specification/dartLangSpec.tex

@@ -7818,9 +7818,10 @@ \subsection{Super-Bounded Types}
 \begin{dartCode}
 \CLASS{} A<X \EXTENDS{} num> \{
   X x;
+  A(this.x);
 \}
 \\
-A<Object> a;
+A<Object?> a;
 \end{dartCode}
 
 \commentary{%