fix completion test expectation for fasta scanner

pkg/analyzer_plugin/test/src/utilities/completion/completion_target_test.dart

 // Copyright (c) 2017, 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.
 
 import 'dart:async';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/src/dart/analysis/driver.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer_plugin/src/utilities/completion/completion_target.dart';
@@ skipping 359 matching lines @@
 
   test_InstanceCreationExpression_keyword2() async {
     // InstanceCreationExpression  ExpressionStatement  Block
     await addTestSource('class C {foo(){var f; {var x;} new^ C();}}');
     await assertTarget('new C();', '{var f; {var x;} new C();}');
   }
 
   test_MapLiteralEntry() async {
     // MapLiteralEntry  MapLiteral  VariableDeclaration
     await addTestSource('foo = {^');
-    await assertTarget(' : ', '{ : }');
+    // fasta scanner inserts synthetic closing '}'
+    await assertTarget('}', '{}');
   }
 
   test_MapLiteralEntry1() async {
     // MapLiteralEntry  MapLiteral  VariableDeclaration
     await addTestSource('foo = {T^');
     await assertTarget('T : ', '{T : }');
   }
 
   test_MapLiteralEntry2() async {
     // SimpleIdentifier  MapLiteralEntry  MapLiteral  VariableDeclaration
@@ skipping 201 matching lines @@
     await addTestSource('main() {int b^ = 1;}');
     await assertTarget('b = 1', 'int b = 1');
   }
 
   test_VariableDeclaration_lhs_identifier_before() async {
     // VariableDeclaration  VariableDeclarationList
     await addTestSource('main() {int ^b = 1;}');
     await assertTarget('b = 1', 'int b = 1');
   }
 }