Format all tests.

tests/language/mixin_extends_field_test.dart

Index: tests/language/mixin_extends_field_test.dart
diff --git a/tests/language/mixin_extends_field_test.dart b/tests/language/mixin_extends_field_test.dart
index dce8fe53e92a15a179f3274bbc67dc3c444c185c..1a80e1b06bab0e6060c0112e284f6132039e5150 100644
--- a/tests/language/mixin_extends_field_test.dart
+++ b/tests/language/mixin_extends_field_test.dart
@@ -16,9 +16,11 @@ class M2 {
   var baz = "M2-baz";
 }
 
-class C extends S with M1 { }
-class D extends S with M1, M2 { }
-class E extends S with M2, M1 { }
+class C extends S with M1 {}
+
+class D extends S with M1, M2 {}
+
+class E extends S with M2, M1 {}
 
 class F extends E {
   var fez = "F-fez";