Format all tests.

tests/language_strong/stacktrace_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.
 
 // Test that a stack trace is properly terminated (issue 8850).
 
 import "package:expect/expect.dart";
 
 void main() {
   var ex = new Exception("fail");
   try {
     throw ex;
-  } on Exception catch(e, st) {
+  } on Exception catch (e, st) {
     Expect.equals(ex, e);
     Expect.isTrue(st.toString().endsWith("\n"));
   }
 }