Fix part related completion tests with the new analysis driver.

pkg/analysis_server/test/services/completion/dart/completion_contributor_util.dart

 // Copyright (c) 2014, 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 test.services.completion.dart.util;
 
 import 'dart:async';
 
 import 'package:analysis_server/plugin/protocol/protocol.dart' as protocol
     show Element, ElementKind;
@@ skipping 419 matching lines @@
     assertHasNoParameterInfo(cs);
     return cs;
   }
 
   /**
    * Return a [Future] that completes with the containing library information
    * after it is accessible via [context.getLibrariesContaining].
    */
   Future<Null> computeLibrariesContaining([int times = 200]) {
     if (enableNewAnalysisDriver) {
-      return new Future.value(null);
+      return driver.getResult(testFile).then((result) => null);
     }
     List<Source> libraries = context.getLibrariesContaining(testSource);
     if (libraries.isNotEmpty) {
       return new Future.value(null);
     }
     if (times == 0) {
       fail('failed to determine libraries containing $testSource');
     }
     context.performAnalysisTask();
     // We use a delayed future to allow microtask events to finish. The
@@ skipping 125 matching lines @@
   }
 
   @override
   void setUp() {
     super.setUp();
     index = createMemoryIndex();
     searchEngine = new SearchEngineImpl(index);
     contributor = createContributor();
   }
 }