Introduce LibraryEntity

pkg/compiler/lib/src/elements/elements.dart

 // Copyright (c) 2012, 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 elements;
 
 import '../common.dart';
 import '../common/resolution.dart' show Resolution;
 import '../compiler.dart' show Compiler;
 import '../constants/constructors.dart';
@@ skipping 886 matching lines @@
 }
 
 abstract class ExportElement extends Element {
   Uri get uri;
   LibraryElement get exportedLibrary;
   // TODO(johnniwinther): Remove this when no longer needed in source mirrors.
   Export get node;
 }
 
 abstract class LibraryElement extends Element
-    implements ScopeContainerElement, AnalyzableElement {
+    implements ScopeContainerElement, AnalyzableElement, LibraryEntity {
   /**
    * The canonical uri for this library.
    *
    * For user libraries the canonical uri is the script uri. For platform
    * libraries the canonical uri is of the form [:dart:x:].
    */
   Uri get canonicalUri;
 
   /// Returns `true` if this library is 'dart:core'.
   bool get isDartCore;
@@ skipping 1000 matching lines @@
   /// by a field.
   bool get isDeclaredByField;
 
   /// Returns `true` if this member is abstract.
   bool get isAbstract;
 
   /// If abstract, [implementation] points to the overridden concrete member,
   /// if any. Otherwise [implementation] points to the member itself.
   Member get implementation;
 }