Add API for contributing to the index

pkg/analysis_server/lib/plugin/index.dart

Index: pkg/analysis_server/lib/plugin/index.dart
diff --git a/pkg/analysis_server/lib/plugin/fix.dart b/pkg/analysis_server/lib/plugin/index.dart
similarity index 61%
copy from pkg/analysis_server/lib/plugin/fix.dart
copy to pkg/analysis_server/lib/plugin/index.dart
index a89b84738cb5957ee1afd190df31dd8553c88791..a6af762dbfa78bfd4a4e1ed69d0d6a67c3ac19b4 100644
--- a/pkg/analysis_server/lib/plugin/fix.dart
+++ b/pkg/analysis_server/lib/plugin/index.dart
@@ -3,20 +3,20 @@
 // BSD-style license that can be found in the LICENSE file.
 
 /**
- * Support for client code that extends the analysis server by adding new fix
+ * Support for client code that extends the analysis server by adding new index
  * contributors.
  */
-library analysis_server.plugin.fix;
+library analysis_server.plugin.index;
 
-import 'package:analysis_server/edit/fix/fix_core.dart';
+import 'package:analysis_server/analysis/index/index_core.dart';
 import 'package:analysis_server/src/plugin/server_plugin.dart';
 import 'package:analyzer/plugin/plugin.dart';
 
 /**
  * The identifier of the extension point that allows plugins to register new
- * fix contributors with the server. The object used as an extension must be a
- * [FixContributor].
+ * index contributors with the server. The object used as an extension must be
+ * an [IndexContributor].
  */
-final String FIX_CONTRIBUTOR_EXTENSION_POINT_ID = Plugin.join(
+final String INDEX_CONTRIBUTOR_EXTENSION_POINT_ID = Plugin.join(
     ServerPlugin.UNIQUE_IDENTIFIER,
-    ServerPlugin.FIX_CONTRIBUTOR_EXTENSION_POINT);
+    ServerPlugin.INDEX_CONTRIBUTOR_EXTENSION_POINT);