do not suggest completions for empty dot target

pkg/analysis_server/test/completion_test.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.completion.support;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:unittest/unittest.dart';
@@ skipping 626 matching lines @@
 class Foo {this.!1}''', <String>["1-Object"], failingTests: '1');
 
     buildTests('testCommentSnippets082', '''
         class HttpRequest {}
         class HttpResponse {}
         main() {
           var v = (HttpRequest req, HttpResp!1)
         }''', <String>["1+HttpResponse"]);
 
     buildTests('testCommentSnippets083', '''
-main() {(.!1)}''', <String>["1-toString"], failingTests: '1');
+main() {(.!1)}''', <String>["1-toString"]);
 
     buildTests('testCommentSnippets083a', '''
-main() { .!1 }''', <String>["1-toString"], failingTests: '1');
+main() { .!1 }''', <String>["1-toString"]);
 
     buildTests('testCommentSnippets083b', '''
 main() { null.!1 }''', <String>["1+toString"], failingTests: '1');
 
     buildTests('testCommentSnippets084', '''
 class List{}class Map{}typedef X = !1Lis!2t with !3Ma!4p;''', <String>[
       "1+Map",
       "2+List",
       "2-Map",
       "3+List",
@@ skipping 1343 matching lines @@
     buildTests('test019', '''
 var truefalse = 0;
 var falsetrue = 1;
 main() {
   var foo = true!1
 }''', <String>["1+true", "1+truefalse", "1-falsetrue"], failingTests: '1');
 
     buildTests('test020', '''var x = null.!1''', <String>["1+toString"],
         failingTests: '1');
 
-    buildTests('test021', '''var x = .!1''', <String>["1-toString"],
-        failingTests: '1');
+    buildTests('test021', '''var x = .!1''', <String>["1-toString"]);
 
-    buildTests('test022', '''var x = .!1;''', <String>["1-toString"],
-        failingTests: '1');
+    buildTests('test022', '''var x = .!1;''', <String>["1-toString"]);
 
     buildTests('test023', '''
 class Map{getKeys(){}}
 class X {
   static x1(Map m) {
     m.!1getKeys;
   }
   x2(Map m) {
     m.!2getKeys;
   }
@@ skipping 260 matching lines @@
       } else {
         ++expectedPassCount;
         tester(testName, () {
           CompletionTestCase test = new CompletionTestCase();
           return test.runTest(spec, extraFiles);
         });
       }
     }
   }
 }