Improve equivalence testing of unnamed mixin applications.

tests/compiler/dart2js/serialization/equivalence_test.dart

Index: tests/compiler/dart2js/serialization/equivalence_test.dart
diff --git a/tests/compiler/dart2js/serialization/equivalence_test.dart b/tests/compiler/dart2js/serialization/equivalence_test.dart
index 443e69983cfbc70c9150aacf55b99f78810f83f1..f6ca1d3380533dfc03af1754235f0852cb925d92 100644
--- a/tests/compiler/dart2js/serialization/equivalence_test.dart
+++ b/tests/compiler/dart2js/serialization/equivalence_test.dart
@@ -391,6 +391,12 @@ class ElementPropertyEquivalence extends BaseElementVisitor<dynamic, Element> {
     } else {
       check(element1, element2, 'sourcePosition.uri',
           element1.sourcePosition.uri, element2.sourcePosition.uri);
+      MixinApplicationElement mixin1 = element1;
+      MixinApplicationElement mixin2 = element2;
+      checkElementIdentities(mixin1, mixin2, 'subclass',
+          mixin1.subclass, mixin2.subclass);
+      checkTypes(mixin1, mixin2, 'mixinType',
+          mixin1.mixinType, mixin2.mixinType);
     }
     checkElementIdentities(
         element1, element2, 'library',