pkg: analysis aided cleanup

pkg/scheduled_test/test/scheduled_test/on_exception_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 'dart:async';
-import 'dart:io';
 
 import 'package:scheduled_test/scheduled_test.dart';
 
 import '../metatest.dart';
 import '../utils.dart';
 
 void main() {
   setUpTimeout();
 
   expectTestsPass('the onException queue is not run if a test is successful',
@@ skipping 52 matching lines @@
       });
 
       pumpEventQueue().then(wrapAsync((_) => expect('foo', equals('bar'))));
     });
 
     test('test 2', () {
       expect(onExceptionRun, isTrue);
     });
   }, passing: ['test 2']);
 }