Specify types in generated closure args.

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

Index: pkg/analysis_server/lib/src/services/completion/dart/utilities.dart
diff --git a/pkg/analysis_server/lib/src/services/completion/dart/utilities.dart b/pkg/analysis_server/lib/src/services/completion/dart/utilities.dart
index b97eb588162eec04b90d514c421e32417720ea41..34630536a0f132e6bba8ea851e493c1a6ab68f0b 100644
--- a/pkg/analysis_server/lib/src/services/completion/dart/utilities.dart
+++ b/pkg/analysis_server/lib/src/services/completion/dart/utilities.dart
@@ -189,7 +189,9 @@ String getDefaultStringParameterValue(ParameterElement param) {
       }
     }
     if (type is FunctionType) {
-      String params = type.parameters.map((p) => p.name).join(', ');
+      String params = type.parameters
+          .map((p) => '${getTypeString(p.type)}${p.name}')
+          .join(', ');
       //TODO(pq): consider adding a `TODO:` message in generated stub
       return '($params) {}';
     }
@@ -198,6 +200,8 @@ String getDefaultStringParameterValue(ParameterElement param) {
   return null;
 }
 
+String getTypeString(DartType type) => type.isDynamic ? '' : '${type.name} ';
+
 bool isDartList(DartType type) {
   ClassElement element = type.element;
   if (element != null) {
@@ -251,4 +255,5 @@ String nameForType(TypeAnnotation type) {
   return DYNAMIC;
 }
 
+//TODO(pq): fix to use getDefaultStringParameterValue()
 String _getDefaultValue(ParameterElement param) => 'null';