Default arg support continued (flutter-intellij#553).

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

Index: pkg/analysis_server/lib/src/services/completion/dart/local_reference_contributor.dart
diff --git a/pkg/analysis_server/lib/src/services/completion/dart/local_reference_contributor.dart b/pkg/analysis_server/lib/src/services/completion/dart/local_reference_contributor.dart
index bbe9d33a09d48f826ba5f2ab02fee3ee9a8786a6..f10cd4b3055996b11e2f7409e2ab2b008a0caa06 100644
--- a/pkg/analysis_server/lib/src/services/completion/dart/local_reference_contributor.dart
+++ b/pkg/analysis_server/lib/src/services/completion/dart/local_reference_contributor.dart
@@ -482,18 +482,7 @@ class _LocalVisitor extends LocalDeclarationVisitor {
     suggestion.hasNamedParameters = namedParameters.isNotEmpty;
 
     suggestion.defaultArgumentListString =
-        _buildDefaultArgList(requiredParameters, namedParameters);
-  }
-
-  String _buildDefaultArgList(Iterable<ParameterElement> requiredParams,
-      Iterable<ParameterElement> namedParams) {
-    List<String> args = requiredParams.map((p) => p.name).toList();
-    List<String> requiredArgs = namedParams
-        .where((p) => p.isRequired)
-        .map((p) => '${p.name}: null')
-        .toList();
-    args.addAll(requiredArgs);
-    return args.join(', ');
+        buildDefaultArgList(requiredParameters, namedParameters);
   }
 
   bool _isVoid(TypeAnnotation returnType) {