Record isFinal for parameters into summaries.

pkg/analyzer/lib/src/dart/element/element.dart

Index: pkg/analyzer/lib/src/dart/element/element.dart
diff --git a/pkg/analyzer/lib/src/dart/element/element.dart b/pkg/analyzer/lib/src/dart/element/element.dart
index 308501bdca3d0589f6582d1b9c1507eefff8cf18..04c2b5fd0326b3ad796f0b58089d079165fc5797 100644
--- a/pkg/analyzer/lib/src/dart/element/element.dart
+++ b/pkg/analyzer/lib/src/dart/element/element.dart
@@ -7163,7 +7163,7 @@ class ParameterElementImpl extends VariableElementImpl
   @override
   bool get isFinal {
     if (_unlinkedParam != null) {
-      return false;
+      return _unlinkedParam.isFinal;
     }
     return super.isFinal;
   }