Format all tests.

tests/lib/async/stack_trace15_test.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:expect/expect.dart';
 import 'package:async_helper/async_helper.dart';
 import 'dart:async';
 
 StackTrace captureStackTrace() {
   try {
     throw 0;
   } catch (e, st) {
     return st;
   }
 }
 
 main() {
   StackTrace trace = captureStackTrace();
   asyncStart();
   var f = new Future(() => 499);
-  f.then((_) => new Future.error("e", trace))
-    .whenComplete(() => 499)
-    .then((_) { throw "should never be reached"; })
-    .then((_) { throw "Unreachable"; },
-      onError: (e, st) {
-        Expect.equals("e", e);
-        Expect.identical(trace, st);
-        asyncEnd();
-      });
+  f.then((_) => new Future.error("e", trace)).whenComplete(() => 499).then((_) {
+    throw "should never be reached";
+  }).then((_) {
+    throw "Unreachable";
+  }, onError: (e, st) {
+    Expect.equals("e", e);
+    Expect.identical(trace, st);
+    asyncEnd();
+  });
 }