Fix typo in mixin test.

Change-Id: I1c6300dfa250ef0b9ea84e9bd5fd233eb5827464
Reviewed-on: https://dart-review.googlesource.com/74960
Commit-Queue: Lasse R.H. Nielsen <lrn@google.com>
Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>
diff --git a/tests/language_2/mixin_declaration/mixin_declaration_syntax_test.dart b/tests/language_2/mixin_declaration/mixin_declaration_syntax_test.dart
index 3c139bb..67de657 100644
--- a/tests/language_2/mixin_declaration/mixin_declaration_syntax_test.dart
+++ b/tests/language_2/mixin_declaration/mixin_declaration_syntax_test.dart
@@ -382,5 +382,5 @@
     }
   }
 
-  Expect equals(CeOwithM().toString(), CwithM().toString());
+  Expect.equals(CeOwithM().toString(), CwithM().toString());
 }