Improve 'length' instance property reference encoding.

pkg/analyzer/lib/src/summary/format.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.
 //
 // This file has been automatically generated.  Please do not edit it manually.
 // To regenerate the file, use the script "pkg/analyzer/tool/generate_files".
 
 library analyzer.src.summary.format;
 
 import 'base.dart' as base;
@@ skipping 18 matching lines @@
    * The entity is a static const field.
    */
   constField,
 
   /**
    * The entity is a static method.
    */
   staticMethod,
 
   /**
+   * The `length` property access.
+   */
+  length,
+
+  /**
    * The entity is a typedef.
    */
   typedef,
 
   /**
    * The entity is a top level function.
    */
   topLevelFunction,
 
   /**
@@ skipping 6049 matching lines @@
     "type": type,
     "constExpr": constExpr,
     "isStatic": isStatic,
     "isFinal": isFinal,
     "isConst": isConst,
     "propagatedTypeSlot": propagatedTypeSlot,
     "inferredTypeSlot": inferredTypeSlot,
   };
 }