Record HAS_ANCESTOR relations into index.

pkg/analysis_server/lib/src/services/index/index.dart

Index: pkg/analysis_server/lib/src/services/index/index.dart
diff --git a/pkg/analysis_server/lib/src/services/index/index.dart b/pkg/analysis_server/lib/src/services/index/index.dart
index 04e57ae9770700f8af6c80be04a41abb9a992302..3a44b4f39b93f73222151e9cd4210ab8c0e77513 100644
--- a/pkg/analysis_server/lib/src/services/index/index.dart
+++ b/pkg/analysis_server/lib/src/services/index/index.dart
@@ -143,6 +143,14 @@ class IndexConstants {
 
   /**
    * Left: class.
+   *   Has ancestor (extended or implemented, directly or indirectly).
+   * Right: other class declaration.
+   */
+  static final RelationshipImpl HAS_ANCESTOR =
+      RelationshipImpl.getRelationship("has-ancestor");
+
+  /**
+   * Left: class.
    *   Is extended by.
    * Right: other class declaration.
    */