Add support for specifying files needing analysis

pkg/analysis_server/lib/plugin/completion.dart

Index: pkg/analysis_server/lib/plugin/completion.dart
diff --git a/pkg/analysis_server/lib/plugin/completion.dart b/pkg/analysis_server/lib/plugin/completion.dart
index a1947e5ab6f7e817311601527b23274f3c7908e9..8fd6159b783a5672789c4521456e242423ad3556 100644
--- a/pkg/analysis_server/lib/plugin/completion.dart
+++ b/pkg/analysis_server/lib/plugin/completion.dart
@@ -13,9 +13,9 @@ import 'package:analysis_server/src/plugin/server_plugin.dart';
 import 'package:plugin/plugin.dart';
 
 /**
- * The identifier of the extension point that allows plugins to register new
- * code completion contributors with the server. The object used as an extension
- * must be a [CompletionContributor].
+ * The identifier of the extension point that allows plugins to register code
+ * completion contributors. The object used as an extension must be a
+ * [CompletionContributor].
  */
 final String COMPLETION_CONTRIBUTOR_EXTENSION_POINT_ID = Plugin.join(
     ServerPlugin.UNIQUE_IDENTIFIER,