Revert "Parts must start with 'part of'" and "Attempt to fix VM build"

dart/lib/compiler/implementation/lib/native_helper.dart

Index: dart/lib/compiler/implementation/lib/native_helper.dart
diff --git a/dart/lib/compiler/implementation/lib/native_helper.dart b/dart/lib/compiler/implementation/lib/native_helper.dart
index 0b4949217b82ded767ff46ff63f5d22450d503f8..1ff2e1c098d8dba355251d3427425d78844c55b7 100644
--- a/dart/lib/compiler/implementation/lib/native_helper.dart
+++ b/dart/lib/compiler/implementation/lib/native_helper.dart
@@ -2,8 +2,6 @@
 // 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.
 
-part of js_helper;
-
 String typeNameInChrome(obj) {
   String name = JS('String', "#.constructor.name", obj);
   if (name == 'Window') return 'DOMWindow';