Run formatter on a few frontend and kernel files that hadn't been formatted.

pkg/front_end/testcases/rasta/super_mixin.dart

Index: pkg/front_end/testcases/rasta/super_mixin.dart
diff --git a/pkg/front_end/testcases/rasta/super_mixin.dart b/pkg/front_end/testcases/rasta/super_mixin.dart
index a00e829f82ee8f7bb74120a08aecf9eeb67ad348..913db8e74b97f10ca5b4bcbfad1370c0464f96d2 100644
--- a/pkg/front_end/testcases/rasta/super_mixin.dart
+++ b/pkg/front_end/testcases/rasta/super_mixin.dart
@@ -9,11 +9,9 @@ class Super<S> {
   f() => 3;
 }
 
-class C<V> extends Super<V> with Mixin<V> {
-}
+class C<V> extends Super<V> with Mixin<V> {}
 
-class D extends Super with Mixin {
-}
+class D extends Super with Mixin {}
 
 class C2<V> = Super<V> with Mixin<V>;