Revert "Move dart2jslib parts into separate libraries."

tests/compiler/dart2js/private_test.dart

Index: tests/compiler/dart2js/private_test.dart
diff --git a/tests/compiler/dart2js/private_test.dart b/tests/compiler/dart2js/private_test.dart
index 8f7123f5c255a1186d3bb5b6aa6361c9d3fafb9d..5121422a2434b42a096e530dfe70483f52e3a5bf 100644
--- a/tests/compiler/dart2js/private_test.dart
+++ b/tests/compiler/dart2js/private_test.dart
@@ -3,12 +3,12 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:async';
+import "package:expect/expect.dart";
+import "package:async_helper/async_helper.dart";
+import 'mock_compiler.dart';
 
-import 'package:async_helper/async_helper.dart';
 import 'package:compiler/src/io/source_file.dart';
-import 'package:compiler/src/messages.dart' show MessageKind;
-
-import 'mock_compiler.dart';
+import 'package:compiler/src/dart2jslib.dart';
 
 const String PRIVATE_SOURCE_URI = 'src:private';
 const String PRIVATE_SOURCE = '''