fix named param default value code completion

pkg/analysis_server/lib/src/services/completion/optype.dart

Index: pkg/analysis_server/lib/src/services/completion/optype.dart
diff --git a/pkg/analysis_server/lib/src/services/completion/optype.dart b/pkg/analysis_server/lib/src/services/completion/optype.dart
index 69b2af1b1b3ad7684d04a75cd32cda71534a0c9a..7bce7304246950f18b9b0e9182e92c120b7e0771 100644
--- a/pkg/analysis_server/lib/src/services/completion/optype.dart
+++ b/pkg/analysis_server/lib/src/services/completion/optype.dart
@@ -223,6 +223,14 @@ class _OpTypeAstVisitor extends GeneralizingAstVisitor {
   }
 
   @override
+  void visitDefaultFormalParameter(DefaultFormalParameter node) {
+    if (entity == node.defaultValue) {
+      optype.includeReturnValueSuggestions = true;
+      optype.includeTypeNameSuggestions = true;
+    }
+  }
+
+  @override
   void visitDoStatement(DoStatement node) {
     if (identical(entity, node.condition)) {
       optype.includeReturnValueSuggestions = true;