Add 'part of' in dart2js code.

lib/compiler/implementation/util/link_implementation.dart

 // Copyright (c) 2011, 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 util_implementation;
+
 class LinkIterator<T> implements Iterator<T> {
   Link<T> current;
   LinkIterator(Link<T> this.current);
   bool get hasNext => !current.isEmpty;
   T next() {
     T result = current.head;
     current = current.tail;
     return result;
   }
 }
@@ skipping 94 matching lines @@
     length++;
     LinkEntry<T> entry = new LinkEntry<T>(t, null);
     if (head == null) {
       head = entry;
     } else {
       lastLink.tail = entry;
     }
     lastLink = entry;
   }
 }