Install default constructors on broken mixin applications.

pkg/front_end/test/fasta/rasta/class_hierarchy.dart.outline.expect

Index: pkg/front_end/test/fasta/rasta/class_hierarchy.dart.outline.expect
diff --git a/pkg/front_end/test/fasta/rasta/class_hierarchy.dart.outline.expect b/pkg/front_end/test/fasta/rasta/class_hierarchy.dart.outline.expect
index 71d5898ab6ecd5361a45f5bd0204eff14d8f5b32..f77dde6947884efb43d7ff77d0f959237046817c 100644
--- a/pkg/front_end/test/fasta/rasta/class_hierarchy.dart.outline.expect
+++ b/pkg/front_end/test/fasta/rasta/class_hierarchy.dart.outline.expect
@@ -21,6 +21,8 @@ class D extends core::Object {
     throw "Redirection constructor target not found: Missing";
 }
 abstract class Object&Missing extends core::Object {
+  constructor •() → void
+    ;
 }
 static method main() → void
   ;