provide MISSING_RETURN on factory constructors

pkg/analyzer/test/generated/hint_code_test.dart

Index: pkg/analyzer/test/generated/hint_code_test.dart
diff --git a/pkg/analyzer/test/generated/hint_code_test.dart b/pkg/analyzer/test/generated/hint_code_test.dart
index 79cb436237721a895b190310f5e9ae64d77c75bc..9ed41933b10fadac80210e51955437d4ee8aea2e 100644
--- a/pkg/analyzer/test/generated/hint_code_test.dart
+++ b/pkg/analyzer/test/generated/hint_code_test.dart
@@ -1323,6 +1323,17 @@ Future<int> f() async {}
     verify([source]);
   }
 
+  void test_missingReturn_factory() {
+    Source source = addSource(r'''
+class A {
+  factory A() {}
+}
+''');
+    computeLibrarySourceErrors(source);
+    assertErrors(source, [HintCode.MISSING_RETURN]);
+    verify([source]);
+  }
+
   void test_missingReturn_method() {
     Source source = addSource(r'''
 class A {