extract LabelContributor from local reference contributor

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 64fecef3a3cd256d8b08c01fa0a35a3b547a2f30..7b6d62c7fccc71c1043fc18acab8e87f60acf296 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
@@ -12,6 +12,7 @@ import 'package:analysis_server/src/services/completion/dart/combinator_contribu
 import 'package:analysis_server/src/services/completion/dart/completion_manager.dart';
 import 'package:analysis_server/src/services/completion/dart/field_formal_contributor.dart';
 import 'package:analysis_server/src/services/completion/dart/keyword_contributor.dart';
+import 'package:analysis_server/src/services/completion/dart/label_contributor.dart';
 import 'package:analysis_server/src/services/completion/dart/library_member_contributor.dart';
 import 'package:analysis_server/src/services/completion/dart/library_prefix_contributor.dart';
 import 'package:analysis_server/src/services/completion/dart/named_constructor_contributor.dart';
@@ -82,6 +83,8 @@ class DartCompletionPlugin implements Plugin {
     registerExtension(DART_COMPLETION_CONTRIBUTOR_EXTENSION_POINT_ID,
         () => new KeywordContributor());
     registerExtension(DART_COMPLETION_CONTRIBUTOR_EXTENSION_POINT_ID,
+        () => new LabelContributor());
+    registerExtension(DART_COMPLETION_CONTRIBUTOR_EXTENSION_POINT_ID,
         () => new LibraryMemberContributor());
     registerExtension(DART_COMPLETION_CONTRIBUTOR_EXTENSION_POINT_ID,
         () => new LibraryPrefixContributor());