Add SourceRange support to navigation collector

pkg/analyzer_plugin/lib/utilities/navigation/navigation.dart

 // Copyright (c) 2017, 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.
 
 import 'package:analyzer/dart/analysis/results.dart';
 import 'package:analyzer/file_system/file_system.dart';
+import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer_plugin/protocol/protocol.dart';
 import 'package:analyzer_plugin/protocol/protocol_common.dart'
     show ElementKind, Location;
 import 'package:analyzer_plugin/protocol/protocol_generated.dart';
 import 'package:analyzer_plugin/src/utilities/navigation/navigation.dart';
 import 'package:analyzer_plugin/utilities/generator.dart';
 
 /**
  * The information about a requested set of navigation information when
  * computing navigation information in a `.dart` file.
  *
  * Clients may not extend, implement or mix-in this class.
  */
 abstract class DartNavigationRequest implements NavigationRequest {
   /**
    * The analysis result for the file in which the navigation regions are being
    * requested.
    */
   ResolveResult get result;
 }
 
 /**
  * An object that [NavigationContributor]s use to record navigation regions.
  *
  * Clients may not extend, implement or mix-in this class.
  */
 abstract class NavigationCollector {
   /**
+   * Record a new navigation region corresponding to the given [range] that
+   * should navigate to the given [targetLocation].
+   */
+  void addRange(
+      SourceRange range, ElementKind targetKind, Location targetLocation);
+
+  /**
    * Record a new navigation region with the given [offset] and [length] that
    * should navigate to the given [targetLocation].
    */
   void addRegion(
       int offset, int length, ElementKind targetKind, Location targetLocation);
 }
 
 /**
  * An object used to produce navigation regions.
  *
@@ skipping 94 matching lines @@
   /**
    * Return the path of the file in which navigation regions are being requested.
    */
   String get path;
 
   /**
    * Return the resource provider associated with this request.
    */
   ResourceProvider get resourceProvider;
 }