C++: Make the return type a bit more precise.

Author: MathiasVP

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/SsaImpl.qll

@@ -498,7 +498,9 @@ class FinalParameterUse extends UseImpl, TFinalParameterUse {
 
   int getArgumentIndex() { result = p.getIndex() }
 
-  override Node getNode() { finalParameterNodeHasParameterAndIndex(result, p, indirectionIndex) }
+  override FinalParameterNode getNode() {
+    finalParameterNodeHasParameterAndIndex(result, p, indirectionIndex)
+  }
 
   override int getIndirection() { result = indirectionIndex + 1 }