Expose LibraryElementImpl.libraryCycle through LibraryElement.

pkg/analyzer/lib/src/task/dart.dart

 // Copyright (c) 2015, 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.task.dart;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
@@ skipping 1921 matching lines @@
     // by the task model are conservatively invalidated by the
     // IMPORT_EXPORT_SOURCE_CLOSURE dependency below.  If anything reachable
     // from a node is changed, its LIBRARY_CYCLE results will be re-computed
     // here (possibly re-using the result from the element model if invalidation
     // did not cause it to be erased).  In summary, task model dependencies
     // on the import/export source closure ensure that this method will be
     // re-run if anything reachable from this target has been invalidated,
     // and the invalidation code (invalidateLibraryCycles) will ensure that
     // element model results will be re-used here only if they are still valid.
     if (context.analysisOptions.strongMode) {
-      LibraryElementImpl library = getRequiredInput(LIBRARY_ELEMENT_INPUT);
+      LibraryElement library = getRequiredInput(LIBRARY_ELEMENT_INPUT);
       List<LibraryElement> component = library.libraryCycle;
       Set<LibraryElement> filter = new Set<LibraryElement>.from(component);
       Set<CompilationUnitElement> deps = new Set<CompilationUnitElement>();
       void addLibrary(l) {
         if (!filter.contains(l)) {
           deps.addAll(l.units);
         }
       }
       for (LibraryElement l in component) {
         l.importedLibraries.forEach(addLibrary);
@@ skipping 3305 matching lines @@
 
   @override
   bool moveNext() {
     if (_newSources.isEmpty) {
       return false;
     }
     currentTarget = _newSources.removeLast();
     return true;
   }
 }