Changes to make compiler_util a standalone package.

pkg/compiler_util/lib/link.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 dart2js.util;
+library compiler_util.link;
+
+import 'src/link_implementation.dart' show
+    LinkBuilderImplementation,
+    LinkEntry,
+    LinkIterator,
+    MappedLinkIterable;
 
 class Link<T> implements Iterable<T> {
   T get head => throw new StateError("no elements");
   Link<T> get tail => null;
 
   const Link();
 
   Link<T> prepend(T element) {
     return new LinkEntry<T>(element, this);
   }
@@ skipping 147 matching lines @@
 
   /// Returns the number of elements in the list being built.
   final int length;
 
   /// Returns `true` if the list being built is empty.
   final bool isEmpty;
 
   /// Removes all added elements and resets the builder.
   void clear();
 }