Add 'part of' in dart2js code.

lib/compiler/implementation/js_backend/emitter_no_eval.dart

Index: lib/compiler/implementation/js_backend/emitter_no_eval.dart
diff --git a/lib/compiler/implementation/js_backend/emitter_no_eval.dart b/lib/compiler/implementation/js_backend/emitter_no_eval.dart
index f658c936bc21253742aa041d4ca1c1ab3ce167bd..db2463e3c0f94fc9cb11548a516b1d1b6827b5c2 100644
--- a/lib/compiler/implementation/js_backend/emitter_no_eval.dart
+++ b/lib/compiler/implementation/js_backend/emitter_no_eval.dart
@@ -2,6 +2,8 @@
 // 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_backend;
+
 class CodeEmitterNoEvalTask extends CodeEmitterTask {
   CodeEmitterNoEvalTask(Compiler compiler,
                         Namer namer,