Update mirror tests to new mixin application syntax.

tests/lib/mirrors/mixin_application_test.dart

Index: tests/lib/mirrors/mixin_application_test.dart
diff --git a/tests/lib/mirrors/mixin_application_test.dart b/tests/lib/mirrors/mixin_application_test.dart
index c552a1b23ac3ac18b3f57dbaa02e7fe4e4841845..953850c65aa791ea5b92068c92920d760fee1fa7 100644
--- a/tests/lib/mirrors/mixin_application_test.dart
+++ b/tests/lib/mirrors/mixin_application_test.dart
@@ -26,10 +26,10 @@ class Mixin2 {
   m2() {}
 }
 
-typedef MixinApplication = C with Mixin;
-typedef MixinApplicationA = C with Mixin, Mixin2;
+class MixinApplication = C with Mixin;
+class MixinApplicationA = C with Mixin, Mixin2;
 
-typedef UnusedMixinApplication = C with Mixin;
+class UnusedMixinApplication = C with Mixin;
 
 class Subclass extends C with Mixin {
   f() {}