Re-land "Format all multitests"

tests/language/flatten_test.dart

Index: tests/language/flatten_test.dart
diff --git a/tests/language/flatten_test.dart b/tests/language/flatten_test.dart
index 0fa5c2405e9d5ebf4f717a984e0940a8c7464bd1..2ff13e9531e0adce9ee3f35e3c72e31d5d73913e 100644
--- a/tests/language/flatten_test.dart
+++ b/tests/language/flatten_test.dart
@@ -16,7 +16,6 @@ class Divergent<T> implements Future<Divergent<Divergent<T>>> {
   noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
 }
 
-
 test() async {
   // flatten(Derived<int>) = int
   int x = await new Derived<int>(); //# 01: runtime error
@@ -39,4 +38,4 @@ test() async {
 
 main() {
   test();
-}
+}