Move a bunch of src/ files into subdirectories.

lib/src/backend/live_test_controller.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.
 
-library unittest.live_test_controller;
+library unittest.backend.live_test_controller;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:stack_trace/stack_trace.dart';
 
+import '../utils.dart';
 import 'live_test.dart';
 import 'state.dart';
 import 'suite.dart';
 import 'test.dart';
-import 'utils.dart';
 
 /// An implementation of [LiveTest] that's controlled by a [LiveTestController].
 class _LiveTest extends LiveTest {
   final LiveTestController _controller;
 
   Suite get suite => _controller._suite;
 
   Test get test => _controller._test;
 
   State get state => _controller._state;
@@ skipping 119 matching lines @@
   Future _close() {
     if (_isClosed) return new Future.value();
     _onStateChangeController.close();
     _onErrorController.close();
     if (!completer.isCompleted) completer.complete();
 
     if (_onClose != null) return new Future.sync(_onClose);
     return new Future.value();
   }
 }