suppress all dart contributor suggestions in comments

pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library services.completion.dart.manager;
 
 import 'dart:async';
 
 import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:analysis_server/src/provisional/completion/completion_core.dart'
     show CompletionContributor, CompletionRequest;
 import 'package:analysis_server/src/provisional/completion/dart/completion_dart.dart';
 import 'package:analysis_server/src/provisional/completion/dart/completion_plugin.dart';
 import 'package:analysis_server/src/provisional/completion/dart/completion_target.dart';
 import 'package:analysis_server/src/services/completion/completion_core.dart';
+import 'package:analysis_server/src/services/completion/optype.dart';
 import 'package:analysis_server/src/services/search/search_engine.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/context/context.dart'
     show AnalysisFutureHelper, AnalysisContextImpl;
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/engine.dart' hide AnalysisContextImpl;
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/task/dart.dart';
 import 'package:analyzer/task/dart.dart';
-import 'package:analysis_server/src/services/completion/optype.dart';
 
 /**
  * [DartCompletionManager] determines if a completion request is Dart specific
  * and forwards those requests to all [DartCompletionContributor]s.
  */
 class DartCompletionManager implements CompletionContributor {
   @override
   Future<List<CompletionSuggestion>> computeSuggestions(
       CompletionRequest request) async {
     if (!AnalysisEngine.isDartFileName(request.source.shortName)) {
       return EMPTY_LIST;
     }
 
+    DartCompletionRequestImpl dartRequest =
+        await DartCompletionRequestImpl.from(request);
+
+    // Don't suggest in comments.
+    if (dartRequest.target.isCommentText) {
+      return EMPTY_LIST;
+    }
+
     // Request Dart specific completions from each contributor
-    DartCompletionRequestImpl dartRequest =
-        await DartCompletionRequestImpl.from(request);
     List<CompletionSuggestion> suggestions = <CompletionSuggestion>[];
     for (DartCompletionContributor c in dartCompletionPlugin.contributors) {
       suggestions.addAll(await c.computeSuggestions(dartRequest));
     }
     return suggestions;
   }
 }
 
 /**
  * The information about a requested list of completions within a Dart file.
@@ skipping 176 matching lines @@
         dotTarget = node.realTarget;
       }
     }
     if (node is PrefixedIdentifier) {
       if (identical(node.identifier, target.entity)) {
         dotTarget = node.prefix;
       }
     }
   }
 }