Add 'part of' in dart2js code.

lib/compiler/implementation/compile_time_constants.dart

 // Copyright (c) 2012, 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.
 
+part of dart2js;
+
 /**
  * The [ConstantHandler] keeps track of compile-time constants,
  * initializations of global and static fields, and default values of
  * optional parameters.
  */
 class ConstantHandler extends CompilerTask {
   final ConstantSystem constantSystem;
 
   /**
    * Contains the initial value of fields. Must contain all static and global
@@ skipping 793 matching lines @@
             // Use the default value.
             fieldValue = compiler.compileConstant(field);
           }
           jsNewArguments.add(fieldValue);
         },
         includeBackendMembers: true,
         includeSuperMembers: true);
     return jsNewArguments;
   }
 }