Format all files under the sdk/lib directory.

sdk/lib/async/zone.dart

Index: sdk/lib/async/zone.dart
diff --git a/sdk/lib/async/zone.dart b/sdk/lib/async/zone.dart
index 7720be97140645f4a81d48a6f3f223efae3b6d1a..1d4e12247e1de14aad9b8b62ff0b7d89716c0f93 100644
--- a/sdk/lib/async/zone.dart
+++ b/sdk/lib/async/zone.dart
@@ -1381,8 +1381,9 @@ class _RootZone extends _Zone {
 
   ZoneUnaryCallback<R, T> registerUnaryCallback<R, T>(R f(T arg)) => f;
 
-  ZoneBinaryCallback<R, T1, T2>
-      registerBinaryCallback<R, T1, T2>(R f(T1 arg1, T2 arg2)) => f;
+  ZoneBinaryCallback<R, T1, T2> registerBinaryCallback<R, T1, T2>(
+          R f(T1 arg1, T2 arg2)) =>
+      f;
 
   AsyncError errorCallback(Object error, StackTrace stackTrace) => null;