Issue 21377. Specify that navigation regions are sorted and implement it.

pkg/analysis_server/lib/src/generated_protocol.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.
 //
 // This file has been automatically generated.  Please do not edit it manually.
 // To regenerate the file, use the script
 // "pkg/analysis_server/tool/spec/generate_files".
 
 part of protocol;
 /**
@@ skipping 1498 matching lines @@
  *   "regions": List<NavigationRegion>
  * }
  */
 class AnalysisNavigationParams implements HasToJson {
   /**
    * The file containing the navigation regions.
    */
   String file;
 
   /**
-   * The navigation regions contained in the file. Each navigation region
-   * represents a list of targets associated with some range. The lists will
-   * usually contain a single target, but can contain more in the case of a
-   * part that is included in multiple libraries or in Dart code that is
-   * compiled against multiple versions of a package. Note that the navigation
-   * regions that are returned do not overlap other navigation regions.
+   * The navigation regions contained in the file. The regions are sorted by
+   * their offsets. Each navigation region represents a list of targets
+   * associated with some range. The lists will usually contain a single
+   * target, but can contain more in the case of a part that is included in
+   * multiple libraries or in Dart code that is compiled against multiple
+   * versions of a package. Note that the navigation regions that are returned
+   * do not overlap other navigation regions.
    */
   List<NavigationRegion> regions;
 
   AnalysisNavigationParams(this.file, this.regions);
 
   factory AnalysisNavigationParams.fromJson(JsonDecoder jsonDecoder, String jsonPath, Object json) {
     if (json == null) {
       json = {};
     }
     if (json is Map) {
@@ skipping 8698 matching lines @@
     return false;
   }
 
   @override
   int get hashCode {
     int hash = 0;
     hash = _JenkinsSmiHash.combine(hash, newName.hashCode);
     return _JenkinsSmiHash.finish(hash);
   }
 }