Don't allow to extract a closure as a getter.

pkg/analysis_server/test/services/refactoring/extract_method_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.services.refactoring.extract_method;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol.dart';
 import 'package:analysis_server/src/services/correction/status.dart';
@@ skipping 605 matching lines @@
   { 
   } 
 // end
 }
 ''');
     _createRefactoringForStartEndComments();
     return _assertConditionsFatal(
         "Operation not applicable to a while statement's expression and body.");
   }
 
+  test_canExtractGetter_false_closure() async {
+    indexTestUnit('''
+main() {
+  useFunction((_) => true);
+}
+useFunction(filter(String p)) {}
+''');
+    _createRefactoringForString('(_) => true');
+    // apply refactoring
+    await assertRefactoringConditionsOK();
+    expect(refactoring.canCreateGetter, false);
+    expect(refactoring.createGetter, false);
+  }
+
   test_canExtractGetter_false_fieldAssignment() async {
     indexTestUnit('''
 class A {
   var f;
   main() {
 // start
     f = 1;
 // end
   }
 }
@@ skipping 1889 matching lines @@
    * Returns a deep copy of [refactoring] parameters.
    * There was a bug masked by updating parameter instances shared between the
    * refactoring and the test.
    */
   List<RefactoringMethodParameter> _getParametersCopy() {
     return refactoring.parameters.map((p) {
       return new RefactoringMethodParameter(p.kind, p.type, p.name, id: p.id);
     }).toList();
   }
 }