Handle forwarding constructors

pkg/compiler/lib/src/serialization/serialization_util.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dart2js.serialization.util;
 
 import '../common.dart';
 import '../constants/expressions.dart';
 import '../dart_types.dart';
 import '../elements/elements.dart';
@@ skipping 488 matching lines @@
 /// the [Element] is deserialized directly from [elementKey] in [encoder].
 Element deserializeElementReference(
     Element context, Key elementKey, Key nameKey, ObjectDecoder decoder,
     {bool isOptional: false}) {
   Element element = decoder.getElement(elementKey, isOptional: true);
   if (element == null) {
     String elementName = decoder.getString(nameKey, isOptional: isOptional);
     if (elementName == null) {
       return null;
     }
-    assert(invariant(NO_LOCATION_SPANNABLE, context.isConstructor,
-        message: "Unexpected reference of forwarding constructor "
-            "'${elementName}' from $context."));
-    ClassElement superclass = context.enclosingClass.superclass;
+    ClassElement cls;
+    if (context is ClassElement) {
+      assert(invariant(NO_LOCATION_SPANNABLE, context.isNamedMixinApplication,
+          message: "Unexpected reference of forwarding constructor "
+              "'${elementName}' from $context."));
+      cls = context;
+    } else {
+      assert(invariant(NO_LOCATION_SPANNABLE, context.isConstructor,
+          message: "Unexpected reference of forwarding constructor "
+              "'${elementName}' from $context."));
+      cls = context.enclosingClass;
+    }
+    ClassElement superclass = cls.superclass;
     element = superclass.lookupConstructor(elementName);
     assert(invariant(NO_LOCATION_SPANNABLE, element != null,
         message: "Unresolved reference of forwarding constructor "
             "'${elementName}' from $context."));
   }
   return element;
 }