anchor.diff:      CompletionPerformance? completionPerformance;
       if (fileExtension == '.dart' && !unit.isError) {
         final result = unit.result;
  -      var performanceOperation = OperationPerformanceImpl('<root>');
  -
  -      serverResultsFuture = await performanceOperation.runAsync(
  +      var performance = OperationPerformanceImpl('<root>');
  +      serverResultsFuture = performance.runAsync(
           'request',
           (performance) async {
             final thisPerformance = CompletionPerformance(
  
positive.code:           completionPerformance = thisPerformance;
            server.performanceStats.completion.add(thisPerformance);
  
            return _getServerDartItems(
              clientCapabilities,
              unit.result,
              thisPerformance,
              performanceOperation,
              offset,
              triggerCharacter,
              token,
  
negative.code:     }
  
      try {
        final serverSuggestions2 =
            await performance.runAsync('computeSuggestions', (performance) async {
          var contributor = DartCompletionManager(
            budget: CompletionBudget(CompletionBudget.defaultDuration),
            includedElementKinds: includedElementKinds,
            includedElementNames: includedElementNames,
            includedSuggestionRelevanceTags: includedSuggestionRelevanceTags,
          );
  
          // `await` required for `performance.runAsync` to count time.
          return await contributor.computeSuggestions(
            completionRequest,
            performance,
          );
        });
  
        final serverSuggestions = serverSuggestions2.map((serverSuggestion) {
          return serverSuggestion.build();
  