Changes to make compiler_util a standalone package.

pkg/compiler_util/lib/src/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;
+library compiler_util.link_implementation;
+
+import 'dart:collection' show
+    IterableBase;
+
+import '../link.dart' show
+    Link,
+    LinkBuilder;
 
 class LinkIterator<T> implements Iterator<T> {
   T _current;
   Link<T> _link;
 
   LinkIterator(Link<T> this._link);
 
   T get current => _current;
 
   bool moveNext() {
@@ skipping 193 matching lines @@
     }
     throw new StateError("no elements");
   }
 
   void clear() {
     head = null;
     lastLink = null;
     length = 0;
   }
 }