Re-land "Format all multitests"

tests/language/mixin_of_mixin_test.dart

Index: tests/language/mixin_of_mixin_test.dart
diff --git a/tests/language/mixin_of_mixin_test.dart b/tests/language/mixin_of_mixin_test.dart
index a686cf0f5428468f5cadbe981ec8ebf686cb4fdd..fb8d7ffe3f8c38dd6b20ffae54c131bdeed455d8 100644
--- a/tests/language/mixin_of_mixin_test.dart
+++ b/tests/language/mixin_of_mixin_test.dart
@@ -14,23 +14,43 @@
 // with Y { ... }`) then things mixed into the mixin application that
 // M extends are not accessible through C.
 
-class A { a() => null; }
-class B { b() => null; }
-class C { c() => null; }
-class D { d() => null; }
+class A {
+  a() => null;
+}
+
+class B {
+  b() => null;
+}
+
+class C {
+  c() => null;
+}
+
+class D {
+  d() => null;
+}
 
 // Note: by a slight abuse of syntax, `class M1 = A with B, C;` effectively
 // means `class M1 = (A with B) with C;`, therefore M1 declares c(), but it
 // merely inherits a() and b().
 class M1 = A with B, C; // declares c()
 
-class M2 extends M1 { m2() => null; }
-class M3 extends A with B, C { m3() => null; }
+class M2 extends M1 {
+  m2() => null;
+}
+
+class M3 extends A with B, C {
+  m3() => null;
+}
+
 class T1 = D with M1; // declares c()
 class T2 = D with M2; // declares m2()
 class T3 = D with M3; // declares m3()
+
 class T4 extends D with M1 {} // extends a class which declares c()
+
 class T5 extends D with M2 {} // extends a class which declares m2()
+
 class T6 extends D with M3 {} // extends a class which declares m3()
 
 main() {