Dart: Reorganize files

mojo/dart/apptests/dart_apptests/lib/src/io_internet_address_apptests.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 library io_internet_address_apptests;
 
 import 'dart:async';
 import 'dart:io';
 
 import 'package:mojo_apptest/apptest.dart';
@@ skipping 47 matching lines @@
         // Not hit.
         expect(true, isFalse);
       } on OSError catch(e) {
         exceptionCaught = true;
         expect(e.errorCode, isNot(equals(0)));
       }
       expect(exceptionCaught, isTrue);
     });
   });
 }