include library prefix suggestions when suggesting constructors

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 c5ec1b61b2a6ab0339ca2809a85783eddc6a0192..4e025f3113136dd3e9d794e92c3621ed79df833d 100644
--- a/pkg/analysis_server/lib/src/services/completion/imported_computer.dart
+++ b/pkg/analysis_server/lib/src/services/completion/imported_computer.dart
@@ -106,7 +106,7 @@ class _ImportedSuggestionBuilder extends ElementSuggestionBuilder
   }
 
   /**
-   * Add constructor suggestions from the cache.
+   * Add constructor and library prefix suggestions from the cache.
    * To reduce the number of suggestions sent to the client,
    * filter the suggestions based upon the first character typed.
    * If no characters are available to use for filtering,
@@ -119,6 +119,7 @@ class _ImportedSuggestionBuilder extends ElementSuggestionBuilder
     }
     DartCompletionCache cache = request.cache;
     _addFilteredSuggestions(filterText, cache.importedConstructorSuggestions);
+    _addFilteredSuggestions(filterText, cache.libraryPrefixSuggestions);
   }
 
   /**