Remove unused reference to SearchEngine

pkg/analysis_server/lib/src/domain_completion.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 domain.completion;
 
 import 'dart:async';
 
 import 'package:analysis_server/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart';
@@ skipping 212 matching lines @@
         return;
       }
     }
 
     recordRequest(performance, context, source, params.offset);
 
     CompletionRequestImpl completionRequest = new CompletionRequestImpl(
         result,
         context,
         server.resourceProvider,
-        server.searchEngine,
         source,
         params.offset,
         performance,
         server.ideOptions);
 
     String completionId = (_nextCompletionId++).toString();
 
     setNewRequest(completionRequest);
 
     // initial response without results
@@ skipping 85 matching lines @@
   final int replacementOffset;
 
   /**
    * The suggested completions.
    */
   final List<CompletionSuggestion> suggestions;
 
   CompletionResult(
       this.replacementOffset, this.replacementLength, this.suggestions);
 }