Mark some other instances of visibleLength/visibleOffset as informative.

pkg/analyzer/lib/src/summary/idl.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 is an "idl" style description of the summary format.  It
  * contains abstract classes which declare the interface for reading data from
  * summaries.  It is parsed and transformed into code that implements the
  * summary format.
  *
@@ skipping 2319 matching lines @@
    * If [isFunctionTyped] is `true`, the declared return type.  If
    * [isFunctionTyped] is `false`, the declared type.  Absent if the type is
    * implicit.
    */
   @Id(3)
   EntityRef get type;
 
   /**
    * The length of the visible range.
    */
+  @informative
   @Id(10)
   int get visibleLength;
 
   /**
    * The beginning of the visible range.
    */
+  @informative
   @Id(11)
   int get visibleOffset;
 }
 
 /**
  * Enum used to indicate the kind of a parameter.
  */
 enum UnlinkedParamKind {
   /**
    * Parameter is required.
@@ skipping 455 matching lines @@
 
   /**
    * Declared type of the variable.  Absent if the type is implicit.
    */
   @Id(3)
   EntityRef get type;
 
   /**
    * If a local variable, the length of the visible range; zero otherwise.
    */
+  @informative
   @Id(11)
   int get visibleLength;
 
   /**
    * If a local variable, the beginning of the visible range; zero otherwise.
    */
+  @informative
   @Id(12)
   int get visibleOffset;
 }