Move more files around.

test/backend/declarer_test.dart

 // Copyright (c) 2015, 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 'package:unittest/src/backend/declarer.dart';
 import 'package:unittest/src/backend/suite.dart';
 import 'package:unittest/unittest.dart';
 
@@ skipping 306 matching lines @@
 /// Runs the test at [index] defined on [_declarer].
 ///
 /// This automatically sets up an `onError` listener to ensure that the test
 /// doesn't throw any invisible exceptions.
 Future _runTest(int index) {
   var liveTest = _declarer.tests[index].load(_suite);
   liveTest.onError.listen(expectAsync((_) {},
       count: 0, reason: "No errors expected for test #$index."));
   return liveTest.run();
 }