extract StaticMemberContributor from PrefixedElementContributor

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 78fd10948a74d752062df7b87e951d5800a5e8b3..29599bfd69f712ea8605c4b6ab7fd809b94a1f39 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
@@ -13,6 +13,7 @@ import 'package:analysis_server/src/services/completion/dart/completion_manager.
 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/named_constructor_contributor.dart';
+import 'package:analysis_server/src/services/completion/dart/static_member_contributor.dart';
 import 'package:analysis_server/src/services/completion/dart/uri_contributor.dart';
 import 'package:plugin/plugin.dart';
 
@@ -80,6 +81,8 @@ class DartCompletionPlugin implements Plugin {
     registerExtension(DART_COMPLETION_CONTRIBUTOR_EXTENSION_POINT_ID,
         () => new NamedConstructorContributor());
     registerExtension(DART_COMPLETION_CONTRIBUTOR_EXTENSION_POINT_ID,
+        () => new StaticMemberContributor());
+    registerExtension(DART_COMPLETION_CONTRIBUTOR_EXTENSION_POINT_ID,
         () => new UriContributor());
   }