Remove _DeferredClassElement because ClassElementImpl is now lazy.

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 368 matching lines @@
     return null;
   }
 
   /**
    * Return the [AbstractClassElementImpl] of the given [classElement].  May
    * throw an exception if the [AbstractClassElementImpl] cannot be provided
    * (should not happen though).
    */
   static AbstractClassElementImpl getImpl(ClassElement classElement) {
     if (classElement is ClassElementHandle) {
-      classElement.ensureActualElementComplete();
       return getImpl(classElement.actualElement);
     }
     return classElement as AbstractClassElementImpl;
   }
 }
 
 /**
  * For AST nodes that could be in both the getter and setter contexts
  * ([IndexExpression]s and [SimpleIdentifier]s), the additional resolved
  * elements are stored in the AST node, in an [AuxiliaryElements]. Because
@@ skipping 7793 matching lines @@
 
   @override
   void visitElement(Element element) {
     int offset = element.nameOffset;
     if (offset != -1) {
       map[offset] = element;
     }
     super.visitElement(element);
   }
 }