Expose LibraryElementImpl.libraryCycle through LibraryElement.

pkg/analyzer/lib/src/dart/element/element.dart

 // Copyright (c) 2014, 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.
 
 library analyzer.src.dart.element.element;
 
 import 'dart:collection';
 import 'dart:math' show min;
 
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 3227 matching lines @@
     }
     return false;
   }
 
   @override
   ElementKind get kind => ElementKind.LIBRARY;
 
   @override
   LibraryElement get library => this;
 
+  @override
   List<LibraryElement> get libraryCycle {
     if (_libraryCycle != null) {
       return _libraryCycle;
     }
 
     // Global counter for this run of the algorithm
     int counter = 0;
     // The discovery times of each library
     Map<LibraryElementImpl, int> indices = {};
     // The set of scc candidates
@@ skipping 1558 matching lines @@
 
   @override
   void visitElement(Element element) {
     int offset = element.nameOffset;
     if (offset != -1) {
       map[offset] = element;
     }
     super.visitElement(element);
   }
 }