remove duplicate completion suggestions

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

Index: pkg/analysis_server/lib/src/services/completion/imported_computer.dart
diff --git a/pkg/analysis_server/lib/src/services/completion/imported_computer.dart b/pkg/analysis_server/lib/src/services/completion/imported_computer.dart
index 5a06b216d6c7a52efa60398e057116080a2f51d7..e8da6efa37dc25faa45492c82bbf09995fbaa2c1 100644
--- a/pkg/analysis_server/lib/src/services/completion/imported_computer.dart
+++ b/pkg/analysis_server/lib/src/services/completion/imported_computer.dart
@@ -80,9 +80,14 @@ class _ImportedSuggestionBuilder extends ElementSuggestionBuilder
   final DartCompletionRequest request;
   final OpType optype;
   DartCompletionCache cache;
+  HashSet<String> completions;
 
   _ImportedSuggestionBuilder(this.request, this.optype) {
     cache = request.cache;
+    completions = new HashSet<String>();
+    for (CompletionSuggestion suggestion in request.suggestions) {
+      completions.add(suggestion.completion);
+    }
   }
 
   @override
@@ -170,11 +175,11 @@ class _ImportedSuggestionBuilder extends ElementSuggestionBuilder
     unfiltered.forEach((CompletionSuggestion suggestion) {
       if (filterText.length > 0) {
         if (suggestion.completion.startsWith(filterText)) {
-          request.suggestions.add(suggestion);
+          _addSuggestion(suggestion);
         }
       } else {
         if (suggestion.relevance != DART_RELEVANCE_LOW) {
-          request.suggestions.add(suggestion);
+          _addSuggestion(suggestion);
         }
       }
     });
@@ -221,6 +226,16 @@ class _ImportedSuggestionBuilder extends ElementSuggestionBuilder
   }
 
   /**
+   * Add suggestion if an identically named suggestion
+   * has not already been added.
+   */
+  void _addSuggestion(CompletionSuggestion suggestion) {
+    if (completions.add(suggestion.completion)) {
+      request.suggestions.add(suggestion);
+    }
+  }
+
+  /**
    * Add suggested based upon imported elements.
    */
   void _addSuggestions(AstNode node) {