Fix the rest of the completion tests with the new analysis driver.

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/plugin/protocol/protocol.dart';
 import 'package:analysis_server/src/analysis_server.dart';
@@ skipping 120 matching lines @@
     // extract and validate params
     CompletionGetSuggestionsParams params =
         new CompletionGetSuggestionsParams.fromRequest(request);
 
     AnalysisResult result;
     AnalysisContext context;
     Source source;
     if (server.options.enableNewAnalysisDriver) {
       result = await server.getAnalysisResult(params.file);
 
-      if (result == null) {
+      if (result == null || !result.exists) {
         server.sendResponse(new Response.unknownSource(request));
         return;
       }
 
       if (params.offset < 0 || params.offset > result.content.length) {
         server.sendResponse(new Response.invalidParameter(
             request,
             'params.offset',
             'Expected offset between 0 and source length inclusive,'
             ' but found ${params.offset}'));
@@ skipping 125 matching lines @@
   final int replacementOffset;
 
   /**
    * The suggested completions.
    */
   final List<CompletionSuggestion> suggestions;
 
   CompletionResult(
       this.replacementOffset, this.replacementLength, this.suggestions);
 }