Fix for completion after the closing quote in a directive.

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'
@@ skipping 211 matching lines @@
   }
 
   OpType get opType {
     if (_opType == null) {
       _opType = new OpType.forCompletion(target, offset);
     }
     return _opType;
   }
 
   @override
-  String get sourceContents => context.getContents(source)?.data;
+  String get sourceContents {
+    if (result != null) {
+      return result.content;
+    } else {
+      return context.getContents(source)?.data;
+    }
+  }
 
   @override
   SourceFactory get sourceFactory {
     return context?.sourceFactory ?? result.sourceFactory;
   }
 
   /**
    * Throw [AbortCompletion] if the completion request has been aborted.
    */
   void checkAborted() {
@@ skipping 294 matching lines @@
           if (start <= requestOffset && requestOffset <= end) {
             // Replacement range for import URI
             return new ReplacementRange(start, end - start);
           }
         }
       }
     }
     return new ReplacementRange(requestOffset, 0);
   }
 }