Plug VariableNameContributor contributor into completion_plugin.dart

pkg/analysis_server/lib/src/provisional/completion/dart/completion_plugin.dart

Index: pkg/analysis_server/lib/src/provisional/completion/dart/completion_plugin.dart
diff --git a/pkg/analysis_server/lib/src/provisional/completion/dart/completion_plugin.dart b/pkg/analysis_server/lib/src/provisional/completion/dart/completion_plugin.dart
index ea6b4896ca7289b8c56e8bd3f2c9482b294b1eaa..cf34c94ee8357b8a9a58e21bd3e1ca5197afeba4 100644
--- a/pkg/analysis_server/lib/src/provisional/completion/dart/completion_plugin.dart
+++ b/pkg/analysis_server/lib/src/provisional/completion/dart/completion_plugin.dart
@@ -24,6 +24,7 @@ import 'package:analysis_server/src/services/completion/dart/named_constructor_c
 import 'package:analysis_server/src/services/completion/dart/static_member_contributor.dart';
 import 'package:analysis_server/src/services/completion/dart/type_member_contributor.dart';
 import 'package:analysis_server/src/services/completion/dart/uri_contributor.dart';
+import 'package:analysis_server/src/services/completion/dart/variable_name_contributor.dart';
 import 'package:plugin/plugin.dart';
 
 /**
@@ -115,6 +116,8 @@ class DartCompletionPlugin implements Plugin {
         () => new TypeMemberContributor());
     registerExtension(DART_COMPLETION_CONTRIBUTOR_EXTENSION_POINT_ID,
         () => new UriContributor());
+    registerExtension(DART_COMPLETION_CONTRIBUTOR_EXTENSION_POINT_ID,
+        () => new VariableNameContributor());
   }
 
   /**